The Ending of '3 Body Problem', Explained

Our guide to the lingering questions after season 1, from "What are sophons?" to "What is a Wallfacer?"

Jess Hong as Jin Cheng, John Bradley as Jack Rooney in episode 103 of 3 Body Problem
(Image credit: Ed Miller/Netflix)

Netflix's new sci-fi series 3 Body Problem is a new take on an age-old question in speculative fiction: What would happen if humans made contact with aliens? Adapted from Liu Cixin's award-winnng Remembrance of Earth's Past book trilogy, the eight-episode series crosses time and space to depict the start of a centuries-long humanitarian conflict with the San-Ti, an extraterrestrial species on its way to Earth to take refuge from the inevitable demise of their own planet. 3 Body Problem's first season covers the human race's discovery of the San-Ti (which takes place decades after the aliens first communicated with one lone scientist) and early efforts to ensure our survival once they arrive, setting up an intricate, layered plot that will hopefully play out over many future seasons. It also introduces viewers to a heap of new scientific terms, both real and fictional, as preparations for the upcoming war play out across the globe. For anyone wondering where everything stands by the end of season 1, here's our breakdown of the 3 Body Problem season 1 ending, including every plot thread the finale sets up for a possible 3 Body Problem season 2.

What are Sophons?

First, a quick rundown of what exactly humanity is up against. In episode 5, genius physicist Jin (played by rising star Jess Hong) and cutthroat operative Wade discover that the San-Ti have been learning about human life and science for decades using a pair of "sophons." These are proton-sized (a.k.a smaller than you can even imagine) multidimensional supercomputers that are tasked with spying on mankind and sabotaging our scientific and technological advancements so humans will be less of a threat once the San-Ti arrive in 400 years. Every particle accelerator on the globe being hacked? Sophons. Every screen in the world reading "You are bugs"? Them too.

a woman warrior (Sea Shimooka as Sophon) with a sword on her back, in episode 105 of 3 Body Problem

The VR avatar credited as Sophon (Sea Shimooka), in '3 Body Problem' season 1.

(Image credit: Ed Miller/Netflix)

In addition to their surveillance and tech capabilities, the sophons can also alter the human mind and vision. They put the countdown in Auggie's (and many other scientists, including Vera's) heads, and they also made everyone on the planet see the stars flicker and the Inception/Doctor Strange vision of the ground reflected on the sky and a giant eye looking at them. (Also, if this isn't confusing enough, the warrior avatar in the San-Ti's VR recruitment game, played by Sea Shimooka, is also credited as Sophon.)

So, the San-Ti have insane tech, the ability to alter human perception, and a possibly 60-year head start. What do the humans come up with?

What is the Wallfacer Project?

In the finale, the U.N. announces the start of the Wallfacer Project, in which three individuals are given the authority and unlimited resources to develop strategic plans against the San-Ti without having to divulge their true intentions to anyone. This is designed to utilize the biggest advantage humans have over the San-Ti: the ability to lie. The San-Ti communicate via thought, so whatever they think is instantaneously known by the other person; when Mike Evans introduces them to the concept of lying and storytelling in episode 4, they don't understand at all. In fact, that's the moment when they get spooked and decide that humans are too dangerous to work with, and instead we should be exterminated like the dishonest, destructive "bugs" we are. And since sophons can't read minds, lying remains the one advantage humans have over the invading aliens.

Jonathan Pryce as Mike Evans in episode 105 of 3 Body Problem

Mike Evans (Jonathan Pryce) tries to communicate with the unresponsive San-Ti, in season 1, episode 5.

(Image credit: Ed Miller/Netflix)

In a meeting with the world's leaders, where the sophons are very likely watching, the three Wallfacers are announced: decorated military general Hou Bolin, esteemed professor Leyla Ariç, and...Saul Durand, an ordinary civilian (well, he's a physics PhD, but still) and member of the Oxford Five. The decision confuses experts and pundits around the world, who have never heard of this guy. It also confuses Saul himself, who, as we've seen throughout the season, lives his life with as little responsibility as possible. When he questions the U.N.'s Secretary-General about the decision, all she says is that "the enemy knows why" he was chosen. Since the San-Ti thinks he's special (and repeatedly try to kill him), they likely see him as a threat.

Why is Saul so important?

Jovan Adepo as Saul Durand in episode 102 of 3 Body Problem

Jovan Adepo plays Oxford Five member Saul Durand in '3 Body Problem.'

(Image credit: Ed Miller/Netflix)

At the start of the finale, Saul wakes up to a relatively normal morning. His latest hookup engages him in some debate on whether humans living now should care about the San-Ti invasion in 400 years (he argues no), before a random car's self-driving feature engages and mows her down. He's picked up by Detective Clarence "Da" Shi, who tells Saul that he was the one meant to die in the car accident, and that someone's targeting him. Fast forward to later that day after the Wallfacer ceremony, and Saul's shot by a sniper outside the U.N. Thankfully, he was wearing a bulletproof suit courtesy of Da Shi, so he's fine.

In the hospital, Saul demands to see the shooter that the police apprehended. (Though Saul had turned down the Wallfacer role, it seems like the position's non-revokable.) The shooter is a San-Ti cultist, who only says "sorry I didn't aim for your head." Saul speaks to the secretary-general again, and she points out that it matters that people (and the always-watching San-Ti) believe that Saul is a Wallfacer. After all, he could just be pretending not to accept the position. All Saul's left with is "you'll know [why you were chosen] when the time is right."

Liam Cunningham as Wade in episode 104 of 3 Body Problem

Intelligence mastermind Wade (Liam Cunningham), with a San-Ti VR headset, in '3 Body Problem' season 1.

(Image credit: Ed Miller/Netflix)

So does Saul remain a Wallfacer? Short answer...yes, but it's not like he has a choice. The real question is whether he'll rise to the occasion. Through all the time we've spent with Saul over eight episodes, we know he's a loyal friend and a talented researcher, but beyond that he's a cynic who'd rather spend his days high and sleeping with women whose names he often doesn't remember. However, we have also seen that he is truly brilliant when he actually uses his brain, so it's possible he'll end up being humanity's secret weapon. One hint in lieu of spoilers: Remember when Saul met with Ye Wenjie in episode 7, and she told him that random joke about Einstein in heaven with the violin? At the end of their conversation she says, "I hope my joke doesn't cause you any trouble." Keep that in mind for later seasons.

Does Project Staircase succeed?

Liam Cunningham as Wade, Jess Hong as Jin Cheng in episode 108 of 3 Body Problem

Wade (Liam Cunningham) and Jin Cheng (Jess Hong) monitor the Staircase Project launch in the season 1 finale.

(Image credit: Ed Miller/Netflix)

Before the Wallfacer Project was announced, the big mission the show centered on was Wade's plan to send a probe to the San-Ti fleet. It was a pretty farfetched idea proposed by Jin, where a capsule with an attached radiation sail would be propelled to light speed by a series of nuclear explosions, getting faster and faster as each bomb detonates. Since the capsule would have to be very light to pull this off, and Wade was dead-set on sending a living human to meet the aliens, he decides the only option is a cryogenically-frozen human brain. If the mission succeeds, the San-Ti will want to revive the brain to get any possible information on the human mind, and if they make the brain a new body, the person will find out how to send intel on the San-Ti back to earth. (Seems like a lot of ifs and a big assumption that the San-Ti would be benevolent hosts, but OK, go ahead and try it.)

Alex Sharp as Will Downing in episode 107 of 3 Body Problem

Alex Sharp plays Will Downing in '3 Body Problem.'

(Image credit: Chris Baker/Netflix)

Try it they did, but in a devastating blow, one of the brackets on the radiation sail breaks off and the capsule goes off course, in both an unknown direction and not anywhere close to a high-enough speed. The plan was wild from the start, but the tragic bent comes from whose brain is in the capsule: Will Downing, one of the Oxford Five and the man who Jin just realized may actually be the love of her life. Will received a fatal cancer diagnosis at the start of the series, and when he learned about Staircase he decided to end his life (or maybe just pause it?) with the hope of saving humanity. Though Jin points out in the final scene that it'll be millions of years before Will's capsule leaves the Milky Way, there's still a chance that he'll have a role to play in the series's future. (Hint hint, read the books if you want spoilers.)

What will the San-Ti do next? (And how does it involve Tatiana?)

Marlo Kelly as Tatiana in episode 104 of 3 Body Problem

Marlo Kelly plays San-Ti ally and assassin Tatiana in '3 Body Problem.'

(Image credit: Ed Miller/Netflix)

As if the failure of Project Staircase isn't enough of a bummer to end season 1 on, there are also two scenes that show that the San-Ti have even more terrifying plans for the war against humanity. Throughout the series, the aliens have had an especially chilling human helper: Tatiana. The mysterious assassin grew up in the San-Ti worshipping cult and is entirely devoted to them, but she's initially abandoned by the San-Ti when they discover that humans can lie. However, in episode 7, Sophon (the VR avatar) appears to her and tells her that they need her.

They send her to the abandoned Red Coast Base in China, where Ye Wenjie first made contact with the San-Ti all those years ago. Ye has also traveled to the base as she reckons with her decision that ended up possibly dooming humanity. In their emotional conversation, Tatiana comforts Ye, telling her that she fulfilled her purpose, and promises "something beautiful" for the physicist. Viewers are left with the two women watching the sunset together, before Tatiana kills Ye offscreen. (Though the scene's a bit ambiguous, Da Shi confirms that Ye did die.)

Rosalind Chao as Ye Wenjie in episode 107 of 3 Body Problem

Ye Wenjie (Rosalind Chao) returns to the Red Coast Base in season 1, episode 7.

(Image credit: Maria Heras/Netflix)

Tatiana also briefly shows up in the finale, as she's sent a silver VR headset by the San-Ti. We don't see what happens when she puts it on, but it's assumed that they're briefing her on next steps. Sophon (again, the VR avatar) also gets a cool standoff with Wade as the boss is aboard a private jet. She shares her condolences that Project Staircase failed, before saying that the San-Ti hope to meet Wade one day if his new hibernation tech works. (He and assumedly some other head scientists plan to hibernate to extend their lives until the San-Ti come.) She also says that Wade's "a part of [their] plan" and that they'll be watching him every day until the end of his life. Sophon even appears as a full-body vision and makes Wade see his own corpse with the eyes gouged out. A fun way to strike fear of the San-Ti into his heart and ours.

What will happen in season 2?

The final scene of season 1 is a bittersweet conclusion to a TV show where the entire world is pushed into existential crisis. Jin and Saul are mourning the loss (physically, if not literally) of their friend Will, and drowning their sorrows realizing that humanity is extremely outmatched. As Jin points out, humans are in fact bugs compared to the San-Ti, and left spinning their heels after their ambitious plan failed. However, Da Shi gives them a pep talk by pointing out something about bugs: no matter how much humans try to exterminate them and stamp them out, bugs aren't going anywhere. It's like that saying: At the end of time, all that will be left is cockroaches. Humanity is resilient, and if we don't let some existential crisis keep us down, we'll endure.

Jess Hong as Jin Cheng, Jovan Adepo as Saul Durand in episode 108 of 3 Body Problem

Jin (Jess Hong) and Saul (Jovan Adepo) in the final scene of the '3 Body Problem' season 1 finale.

(Image credit: Macall Polay/Netflix)

You'll have to read Cixin Liu's book trilogy to get the full spoilers for the future of the TV series, but here's some basic details: After the start of the Wallfacer Project, the next book, The Dark Forest, follows Saul as he reckons with his new assignment and eventually becomes an integral part of the conflict against the San-Ti. Meanwhile, the San-Ti come up with their own response to the Wallfacer Project, called the Wallbreakers. (I leave you with some curiosity about that fantastic name.) Jin also remains involved in the events going forward; as hinted by season 1's final scene, Saul and Jin will likely get plenty of screen time as the remaining members of the Oxford Five. The book character that's closest to Auggie (Wang Miao) doesn't get much to do past the events already covered in the show, but it's possible that the TV's version could find a reason for her to come back.

Quinci LeGardye
Contributing Culture Editor

Quinci LeGardye is a Contributing Culture Editor who covers TV, movies, Korean entertainment, books, and pop culture. When she isn’t writing or checking Twitter, she’s probably watching the latest K-drama or giving a concert performance in her car.