As a prologue in 2114, RJ Brewster meets with Dr. Carter Ramirez and Prakash Das, a spy for the Sino-Russian Bloc, for lunch. RJ has been having a very hard time re-acclimating to life after being lost. Ey has lost eir job due to fears around delving in, and eir cat has passed away. Ey considers Dr. Ramirez and Sasha eir only remaining friends. After lunch, Prakash catches up with RJ and offers to bring em in on a project to create a new embedded world with uploaded consciousnesses based around the information learned from the lost.
Part 1 — Anticipation
In 2346, more than twenty years after the two smaller versions of the System, Castor and Pollux, were launched out of the solar system, someone has picked up on the signal transmitted by the "Dreamer Module", a part of the launch vehicles containing scientific instruments as well as some recordings as a way to possibly get in touch with extraterrestrial life on the journey.
Tycho Brahe, the astronomer on call (and one of Codrin Bălan's interviewees for the History), has received a message from a passing vehicle claiming that they are nearby and understand the mechanism by which consciousnesses may be transferred between ships, stating that they have similar and would like to meet. Tycho, without thinking, grants them consent to do so, and promptly freaks the fuck out.
Unsure of where to turn, ey contacts Codrin and visits em and eir partner, Dear, Also, The Tree That Was Felled, early in the morning, explaining what happened, that there will likely be alien visitors before long, and that it's all his fault. They talk him down from his panic and send him on his way back to his sim, an observatory of sorts.
Back at his sim, he meets up with The Only Time I Know My True Name Is When I Dream, who has, in the past, helped steer the direction of both the System and life on Earth through subtle political manipulation. Despite his anxiety, she's really quite nice to him and invites him to fork (creating Tycho#Artemis) and come work with her and Jonas Anderson on the project of first contact.
There, he meets one of True Name's cocladists, Why Ask Questions When The Answers Will Not Help. They share the next message that has arrived, offhandedly mentioning that they are now gating communication with the remote ship (which they have dubbed Artemis). The message contains a set of instructions for how better to align Castor to Artemis for transmission as well as for a space to create in order to have conversations in person. True Name explains that this will take place in the DMZ, an area that is inaccessible to the rest of the System except through a single, tightly controlled access point. The conversations will take place on both Castor and Artemis in similar spaces.
The Artemisians request to meet with a party of five: someone in a leadership role, someone who can act as a recorder/amanuensis, a scientist, and two representatives. They have put forth Turun Ka of firstrace as leader, Turun Ko of firstrace as recorder, Stolon of thirdrace as scientist, and Iska of secondrace and Artante Diria of fourthrace as representatives, implying that there are at least four different uploaded races aboard their craft. In return, they will send True Name as leader, Codrin Bălan as recorder, Tycho as scientist, and another of True Name's cocladists, Why Ask Questions Here At The End Of All Things as a representative, leaving the final representative up to Codrin to choose. Until then, Tycho#Artemis works with Sovanna Soun and Dr. Paolo Verda on the technical side of setting up the meetings, as well as learning some of the Artemisian language that they have provided.
Codrin, meanwhile, discusses some fears with Dear, stating that ey feels like ey's lacking agency, always getting dragged along into these enormous events. They're fun and all, but ey's starting to feel like ey isn't actually doing anything worthwhile. Ey is nothing if not a recorder, though, so ey visits with Tycho's root instance to describe what all will likely happen during this meeting. Back at home, ey discusses the request from True Name with eir partners, and Dear's partner suggests Sarah Genet, their therapist before they uploaded, as someone who is normal, curious, and a grounded.
The team of emissaries (plus Dear) meet up at Tycho's dark-sky sim for dinner, where they discuss their hopes and fears surrounding this summit. They also learn just how under control the situation is by True Name and Jonas, with the announcement of the arrival of Artemis being tightly planned and shaped by the Odists. After, Tycho has a dream about meeting the Artemisians, which leads to sending them a series of questions surrounding their society and lives.
They learn that the Artemisians do not have anything analogous to forking, but instead allow for fine-grained management of time; individuals or groups can move faster or slower than the rest of the world around them, allowing them to get more work done in fast-time or to wait out long periods in slow-time. The Odists (especially Dear) react poorly to this, explaining that it is similar to the experiences they had while lost.
In the twenty years since launch, Castor has made it thirty light-days away from Lagrange (the home System), so it isn't until a month later that Ioan Bălan and May Then My Name Die With Me receive news of first contact, as well as Codrin's thoughts on eir lack of agency. In the interim, they have moved on from their lives as historian and launch coordinator to both start working in theatre under the direction of another Odist, Time Is a Finger Pointing At Itself, with Ioan now writing plays.
They are contacted by the version of True Name that has remained on Lagrange. In the intervening years, May Then My Name has grown to truly hate her down-tree instance, feeling that the way she was manipulated was unfair, and the way she was used to manipulate others rather evil. There is a tense conversation about what knowledge they've received about the Artemisians versus what knowledge True Name has received, as well as all of the ways both True Name and May Then My Name have changed, with the former noticeably more cowed and anxious than she had been twenty years prior. She asks that they not share the information beyond a limited circle until a wider, more controlled announcement can be made. May Then My Name makes her cry and kicks her out of her and Ioan's house.
Tycho watches the news disseminate and how it's being shaped by Odists such as True Name, Why Ask Questions, and Answers Will Not Help. They work out a date to begin the conversation once they are in effective Ansible range with Artemis and discuss what to expect, including the fact that they may not have enough in common with the Artemisians to actually understand them. It's decided between the two parties that the discussions on Castor will surround sharing scientific knowledge and those on Artemis will surround history, society, and psychology.
Part 2 — Experience
The talks begin on both Artemis and Castor. On Artemis, Codrin arrives already 'skewed up' to fast-time, allowing em to see the Artemisians even as they others appear almost frozen at a much slower time scale. There are indeed four types of Artemisians: firstrace, which was described as post-biological, appear to be synthetic constructions that are equally comfortable on two or four legs with six-fingered hands and feet with two opposable thumbs and a thick tail for balance, analogous to a kangaroo. Secondrace is described as looking so close to a weasel that it would be easy to mistake them for Debarre, were it not for how short they are. Thirdrace looks something like a very colorful lizard with scales that shine like an oil slick and a frill of feathers or elongated scales around the crown of their heads. Fourthrace appears almost human, though with their features much smoothed.
Turun Ko, the other recorder, skews up to fast-time to talk with Codrin, where they discuss how, most of the time, people live in 'common time' and shows em how to manipulate time to eir liking. The two Odists are indeed already suffering; Why Ask Questions has collapsed onto the pavement, shifting wildly between human and skunk forms just as Michelle Hadje had, and True Name is using all the energy she has to stay in one form. They are taken to a 'unison room' where time is pinned in place for all occupants while the other three emissaries are taken to their rest area. There, Tycho confides in Codrin that he doesn't think that that was Why Ask Questions but rather Answers Will Not Help.
Back on Castor, greetings go much more smoothly, and the talks begin with a series of questions. Tycho and Stolon, the scientists, hit it off immediately and they have to be reminded several times that this is not simply an astronomy conference. Sarah and Artante also discover that they are both psychologists and share a lot in common.
On Lagrange, May has wound up 'overwhelmed', an experience similar to that which is described as Dear having, where emotions get the best of her and she has to spend time alone in order to bring herself back to baseline. When she is able to do so, she meets up with Ioan and Douglas at Michelle's old field. There, she explains that this episode lasted longer than usual because, toward the end, she was contacted by If I Am To Bathe In Dreams, who has been acting as the Odists' therapist, to meet up with another stanza's worth of Odists, as the first line, May One Day Death Itself Not Die quits without leaving a fork, followed shortly by her up-tree instance, I Do Not Know, I Do Not Know. With Qoheleth gone, this leaves only 97 Odists left. Ioan and Douglas express their concerns that the cracks are starting to show in more of the clade as more of them go mad. Once back home, Ioan and May are intensely gay with each other and totally in love and it's really cute. Also, they discuss the option of the Odists leaning on Sarah Genet as a therapist to help them not all succumb to madness.
Codrin#Castor and Codrin#Artemis exchange notes at the end of the first day, relying on another fork, Codrin#Assist, who ferries them between the DMZ and the rest of Castor where ey can transmit them to Artemis. They describe the first day and what they've learned, including the troubles that True Name and "Why Ask Questions" are experiencing on Artemis, though Codrin#Artemis hints at the fact that there might have been a swap with Answers Will Not Help.
The discussions run into a few problems with mutual misunderstandings, and there is some frustration over the fact that the Artemisians often say "now is not the time to have this conversation" when certain topics are brought up. They power through it, though, and are able to learn some good information from each other, both directly from the conversations as well as from implications, such as the fact that, despite the Artemisians saying that there have been three of these 'convergences' before, they may have met more races than they are letting on, instances where there weren't convergences. True Name has a conversation with Turun Ka about how the Artemisians manage sentiment and steer politically, leading to some concern among the Artemisians. Tycho worries about her being so open about her own manipulations, suggesting that maybe she's losing it with the time skew.
Ioan and May go camping with Douglas, A Finger Pointing, and Do I Know God After The End Waking in the latter's forest sim, where they discuss what it felt like to go lost and how it has left them all a little bit mad. May explains why this business with time skew might bring up those old feelings and why Odists aren't likely to spend much time on Artemis or join, should that be the direction things go in. End Waking says that he would probably try to join anyway, while Douglas says that he's upset that he won't get the chance.
Ioan and Codrin#Pollux exchange letters — since Pollux is thirty days away from Lagrange, information from Castor arrives two months late. Codrin#Pollux offers support to Codrin#Castor on taking control of eir life, explaining how ey took a position as a librarian at a university in the interim. Ey confides in Ioan, however, that ey is worried at how conservative Castor seems, with Dear, Codrin, and True Name all sounding much as they had twenty years prior, while Pollux has moved on: Dear has expanded the sim to include other terrain features, and its cocladist Serene, Sustained And Sustaining joined their polycule for a while, leading to two cocladists in a relationship with each other, something which is still considered taboo on Castor. They discuss how all three Systems have changed, with Lagrange being between Castor and Pollux in terms of conservative/liberal amounts of change.
Part 3 — Intensity
True Name and Answers Will Not Help (as Codrin is now convinced she must be) are really struggling aboard Artemis now, with Answers Will Not Help the worse of the two. She often interrupts the meetings, spouting poetry and then apologizing that she cannot keep from speaking. Additionally, despite the talk taking place in a unison room, she is still somehow able to skew time a little (or unable to keep herself from doing so), which worries Iska, who is a time skew artist, analogous to Dear's instance artistry.
This comes to a head when Answers Will Not Help interrupts with a long, rambling tirade, the end of which includes her saying the Name, more helpless in her crazed state than intentionally, and admitting that she is not Why Ask Questions. True Name confronts her angrily, and when she says it again, the skunk tackles her and, after a short fight, Answers Will Not Help quits. The emissaries should not have been able to skew in the unison room, nor should they have been able to quit, so Iska freaks out and runs off to find a system technician. True Name, now a total mess, admits to the deception, but Turun Ka says that they had expected such, but that conversations around the topic will remain for another time.
While True Name rests, Codrin, Sarah, and Tycho meet up with Turun Ko, Artante Diria, and Stolon to discuss the fact that this whole time, the Artemisians have been following a checklist of steps that might occur during convergence with the goal of ensuring that everyone is safe and as happy as they can manage. The end steps would be either humanity joining them as fifthrace or parting on peaceable terms. Tycho admits that, given the chance, he'd join Artemis, given that he finally feels happy there.
Ioan meets up with True Name on Lagrange to ensure that, even if they aren't fond of each other, there's no enmity in the air between them, that they can be polite to each other. Ey mentions discussions from Castor wherein Dear suggests that "even she must have emotions", which makes True Name cry because of course she does, but she's built a life where she can't show them and no one would believe her. Ioan asks if she's been in touch with Sarah, but she says that no, In Dreams never passed that on, showing that the rest of the clade has all but dropped her.
May has kind of crashed after all these dramatic events going on, falling into a funk, though a more normal one. A trauma response in her is triggered when she starts an introductory session with Sarah and she has to step away, leaving Ioan to unintentionally have a therapy session with Sarah instead, which ey finds super useful. After, ey admits to her that ey's starting to feel a lot of sympathy for True Name, worrying about her.
On Castor, True Name admits to the deception that took place on Artemis (Why Ask Questions having only been replaced for that side of the talks), leading her and Turun Ka to have several conversations separate from the rest of the delegates. During one of these lulls, Codrin discusses the checklist with Sarah, Turun Ko, and Artante.When they admit that there are conversations that they cannot have yet, Codrin gets frustrated and asks if ey can just give them information without necessarily having a conversation. When they say yes, ey gives them a copy of the History that ey wrote around the time of Launch, even if it shows True Name's political machinations. Ey also provides a copy of May's Mythology, saying that the Artemisians deserve more than just the sugar-coated synopses of their society that they've received so far. As its clear that ey shouldn't have done so without True Name's blessing, Sarah objects, but Turun Ko says that this is actually the penultimate step on the checklist: the fact that they still retain individual desire to better all races even in the face of leadership disagreeing, and that the talks between Turun Ka and True Name have been artificial, meant mostly to give the other emissaries the chance to go behind her back.
On learning this on Artemis, the Artemisians wait for the final step in the checklist. When Tycho interrupts a talk to say that he wants to join them, and wants humanity to become fifthrace, the Artemisians welcome them as such, saying that the final step was simply a desire to join and an active decision to do so.
Part 4 — Integration
After the talks and all of their instances have merged back down Tycho heads back to his sim to try and process what happened and is surprised when True Name joins him, saying that she doesn't know how to celebrate anymore, feeling that she isn't a whole person after two and a half centuries, much of that time spent focusing solely on politics. She suggests that eternal memory is clashing with the fact that she's still growing as a person, still changing.
Back at the prairie, Codrin and Sarah catch Dear and its partner up on the happenings in a general way before Codrin invites Dear out on a walk. There, ey explains that Answers Will Not Help said the Name and kept saying "I cannot feel em" throughout the conference, so now ey knows about AwDae. Dear laughs about it, saying that it's the end of the era. It says not to tell any other Odists of course, but that it will become a game between their two clades, because turning it into one will make sure that any other Odists, namely True Name, looking in on them will simply see them goofing off and not actually sharing it. They pass this information on down to Lagrange, telling May about the game and Ioan about the fact that Codrin knows. May explains that this is a way for Codrin to not bear the knowledge alone as well as a way to reduce any culpability between the two clades.
The DMZ is expanded and renamed Convergence, and the Ansible is turned on, allowing as many Artemisians who want to join them to do so, and any humans that want to join Artemis to do that as well. During a conversation with True Name, Tycho decides that he will invest totally in Artemis, leaving no forks behind.
Codrin also decides to send a fork along to Artemis, even though it means that the fork will be alone, since neither of eir partners will be joining. Ey rushes to ensure that the fork is an individual in case that helps, so the fork becomes a woman named Sorina. She's unable to bring herself to say goodbye to her (former) partners, so she leaves without doing so. When ey returns home to eir partners, ey describes what happened, then says that ey actually wants to do something and be proactive, suggesting that they move to Convergence, taking the whole prairie sim with them. Ey also says that ey's getting out of the amanuensis business and going into therapy, since everyone kept saying ey was grounding and ey finds Sarah fascinating.
In the end, Tycho invests fully after giving himself a eulogy at a small party of the emissaries and a few others who worked on the project. His last words are from a poem about his namesake: "Though my soul may set in darkness, it will rise in perfect light. I have loved the stars too fondly to be fearful of the night." He transfers to Artemis where he meets Stolon and joyfully admits that it's finished.
As an epilogue, AwDae is shown going through the process of uploading, wherein the S-R Bloc scientists are shown still trying to create the System. Ey would be the only one, if it's successful, though no previous attempts have been enough to emulate an entire person, except for one other of the lost they tried with, but they were a bit too crazy and self-destructed as soon as they uploaded. When ey finally goes through the procedure, ey gives emself entirely to it and, though ey doesn't survive to exist as a person uploaded, the process of em giving emself so fully to it winds up creating the self-sustaining world that becomes the System, showing that, yes, the Odists really were feeling eir presence throughout the system the whole time, that ey was the origin of the System, and that they originally had to keep eir name secret because at first (though it diminishes later), everyone could feel that presence but didn't know who it was.