The season finale resolves some of the plots that have been going on all season but leaves enough cliffhangers to be resolved in the next season.
First we get some idea about what Lee Jung-Gil, the North Korean astronaut, has been up to and get confirmation that he is the Sole Survivor of his mission and that he did, indeed, land on Mars before any of the others. Months of isolation and his supplies evidently running out drive him to despair, and he is about to commit suicide with a pistol when he spots Danielle and Grigory arriving at his ship. Holding them at gunpoint, Danielle tries to communicate with Lee via dirt drawing before Grigory knocks him out by disabling his suit. Danielle fixes the suit of the North Korean cosmonaut but they agree to take him to Happy Valley as a sorta-kinda-prisoner with Duct Tape shackles.
On Earth the conflict at Helios comes to a head with Karen - acting on Molly's advice, she decides to take over the company after all. Dev tries to sway his employees with a Rousing Speech but Karen manages to deflate him by bringing up the question of his employees' salaries if they stick with him.
Ellen Wilson is visited by her Vice-President, who tells her to resign or face impeachment by her own party. Ellen coolly replies that with support from the Democrats she can avert the two-thirds majority required for impeachment and refuses to cave in. Later Ellen visits Pam's house and the two appear to reconcile.
Meanwhile it is becoming clearer, that Kelly can only get to Phoenix if she is the only one to go there. And even then it requires some risky maneuvers to pull it off. Danny confesses to Ed that it was he who destroyed the drilling rig and volunteers for the near-suicide mission of flying the MSAM to Helios, but Ed angrily rejects the offer and tells him there will be a reckoning later.
Margo is informed by her Soviet counterpart that she is being investigated by the FBI. Aleida briefly confronts her about her espionage, and Margo promises to tell her about it later but for now she needs Aleida to pitch in with resolving the crisis on Mars. Later in the mission control room, after Molly Cobb joins in to help Ed with his flying, Margo tells her staff It Has Been an Honor to work with them all these years and turns command over to Aleida before retiring to her office.
Jimmy is getting cold feet regarding the plot of his "friends" regarding NASA and he seems to be still in the dark as to what it actually entails. Just before he can high-tail it out of there, he gets knocked out. Karen hears him struggling in the van he is tied up in and gets him out as they discover the explosives wired up. As Karen notifies security Jimmy's "friend" sees her and triggers the bomb - and a giant detonation rips NASA HQ apart. The blast kills Karen Baldwin and Molly Cobb along with dozens or hundreds of others, while Aleida visits the remains of Margo's office and sees no trace of her mentor.
Ed successfully delivers his adoptive daughter to Phoenix and makes it back in one piece, only to be informed of the death of Karen.
Meanwhile Sergei and his kin have been successfully extracted from the USSR, allowing him to live out the rest of his life in the US.
Time jump to 2003: Sergei is living a quiet life in the US while Margo is living in exile somewhere in Soviet territory.
- Ace Pilot: Ed once again demonstrates his piloting skills when he manages to return to Mars with little more than a cut on his head.
- Actually Pretty Funny: When they realize how Lee has been here before everyone, meaning he's the first man on Mars, Danielle and Grigory sit there, clearly thinking of everything that's happened from the space race to their fighting to land on the planet first, all the chaos of the last nine episodes, all to win a race already lost...and both can only burst out laughing.
- All for Nothing: NASA and the Soviets pushed everything so that they could match Helios's launch window...and it turns out that all three of them were beaten to Mars by North Korea of all nations.
- Allohistorical Allusion: The bombing of the Johnson Space Center serves as the show's equivalent of the Oklahoma City bombing, which also took place in 1995. With the completion of his story arc, Charles Bernitz parallels Timothy McVeigh by being a former serviceman (McVeigh was in the Army, Charles was a Marine) who had served their nation with distinction before becoming a mass murderer in a domestic terrorist bombing, with the difference being that McVeigh was captured and later executed while Charles is killed setting off the bomb.
- Back for the Dead: Molly had been Put on a Bus after being fired from NASA. She's back for this episode, but dies in the attack on Johnson Space Center.
- Beard of Sorrow: When Lee Jung-Gil lands on Mars, he is clean-shaven. Over the months he does not shave - possibly because he does not have the supplies, but most likely also because he no longer cares. After all, he should've grown quite a bit of beard during the months-long flight, too.
- Bittersweet Ending: Jimmy's "friends" blow up the Johnson Space Center, killing an untold number of people including Karen Baldwin and Molly Cobb. Kelly makes it to Phoenix and gives birth, while the rest of the NASA, Soviet, and Helios crew on Mars will remain there until they are recovered in at least 1998. Danny confesses to causing the drilling accident, leading Ed and Danielle to exile him to the North Korean spacecraft.
- Combat Pragmatist: Grigory is not beneath tackling the North Korean cosmonaut to the ground and disabling his suit while Danielle distracted him with - what appears to be - an honest attempt to diffuse the situation non-violently. In the end it works out for all involved, thankfully.
- Dark Horse Victory: North Korea, the tiny, isolationist totalitarian state that even their Soviet allies can't get a straight answer out of, and who couldn't get a satellite into orbit at the beginning of the season without causing a major disaster, manages to beat both superpowers and the N.G.O. Superpower of Helios by landing on Mars first.
- Death Seeker: Both Danny and Jung-Gil have aspects of this. It is revealed that the reason the latter was holding a gun when we first saw him was that he was about to commit suicide with it.
- Defeat Means Friendship: Danielle and Grigory have had a contentious working relationship during the entire mission, but they seem to get closer after realizing that neither of them made it to Mars first.
- Despair Event Horizon: The North Korean seems to have been driven way over it after being isolated for months without hope of rescue and presumably running out of supplies.
- Enemy Mine: The Democratic leader "Dick" and Ellen have not been anything on the same planet as friends, but with impeachment looming, they have common interests - Ellen wants to stay in office and make a statement against the homophobic wing of the Republicans. Dick wants to prevent a right wing Republican serving out Ellen's term (which would also possibly spell disaster for Democrats in the upcoming Midterms). So whether either of them wants it or not, Ellen will almost certainly stay in office thanks to Democrats voting against impeachment in the House and/or against conviction in the Senate.
- Exact Words: Danielle tells Grigory that maybe they won't need to use words to communicate with Jung-Gil. She starts to explain why they are there using body language and drawings in the soil, and when he's distracted, Grigory rushes him and disconnects his oxygen supply to knock him out.
- The Exile: Danny is sent to man the North Korean space capsule while Colonel Lee stays at the Hab.
- Face–Heel Turn: Charles Bernitz completes his descent by going from a Marine serving his country to a domestic terrorist who kills hundreds of innocent people.
- Fatal Family Photo: Subverted. Colonel Lee has a photo of his wife in the spacecraft, but he manages to survive his time on Mars. He is shown video-chatting with her in the Helios hab.
- Fire-Forged Friendship: By the end of the episode everyone still on Mars (with the possible exception of the North Korean who is now rooming with the three other missions) is on much friendlier terms with one another than Helios NASA and the USSR are back on Earth or their missions were at the start. Just like what happened to Gordo, Danielle and Ed on Jamestown in Season 1, the amount of heartbreak and disaster, as well as the unforgiving Martian environment will either have everyone at everyone's throats - or them getting their shit together and becoming friends. Unfortunately, this does not include Danny Stevens, whose actions have excluded him from the group.
- First-Name Basis: Ellen calls the Soviet leader "Mikhail". The phone-call is also presented as if there were no translator in between, which is extremely unusual given diplomatic protocol to even have a translator if none is needed.
- Freeze-Frame Bonus: The newspaper that Sergei picks up in The Stinger mentions the new JSC-replacement being named after Molly Cobb (what "the Senator for space" LBJ gets in replacement is not mentioned, however). If you freeze the image and zoom in, you realize that it's not just "Lorem Ipsum" and that a) It took them seven days to find Molly's body, and b) The date on the newspaper is not 2003.
- Heroic Sacrifice: Molly leads a group of survivors to a stairwell, then goes back for more. She then dies somewhere in the building.
- Hidden Depths: Just when everyone else is wondering how they're going to communicate with Jung-Gil, Ed Baldwin starts conversing fluently enough with him (albeit calling him "my good dumpling" at one point). Turns out he picked up some Korean during his wartime service.
- Hope Spot: From the perspective of Dev and those rooting for him, his Rousing Speech is one where he almost manages to turn his employees around. But then Karen barges in with an Armor-Piercing Question and the mood turns against him.
- Hourglass Plot: At beginning of the Episode, the North Korean is alone with only a picture of his family for company in a cramped capsule, unsure if anyone has taken notice of his fate, while Danny is surrounded by people who, if not like, at least grudgingly accept his presence and with the opportunity to video-call Earth whenever he wishes. By the end of the episode, their fates are reversed.
- How We Got Here: The episode begins with Colonel Lee arriving on Mars before the NASA-Soviet mission, and shows what he had been doing since his arrival.
- I Choose to Stay: Without hesitation, the remaining NASA, Soviet, and Helios crews choose to remain on Mars so that the MSAM will have enough reduced weight to get Kelly to Phoenix. They also do this to ensure the Mars program continues, necessitating that NASA sends another ship to recover them.
- Irony: Bragg lampshades how Ellen is counting on being saved from impeachment from the Democrats, the very party she's been fighting hard for over two years. Ellen notes that might not have happened had she not come out with the Democrats deciding a gay female President is a lot better to work with than Bragg would be.
- Killed Off for Real: Karen is killed in the bombing. Molly initially survives, but dies in the aftermath.
- Jumping Off the Slippery Slope: The group of conspiracy theorists Jimmy joined were turning militant but the worst we have seen them do is steal a statue of Tracy and Gordo as a form of protest against the NASA coverup. Now they have built a bomb and use it to kill dozens of people. It seems to have taken them a few months to go from what is the equivalent of a college prank to domestic terrorism and mass murder.
- Locked Out of the Loop: Jimmy thinks that his friends are at the JSC for another protest and maybe a bit of civil disobedience. He has zero idea that they plan to explode a bomb.
- My God, What Have I Done?: Jimmy Stevens is more than shaken in the aftermath of the bombing.
- No One Gets Left Behind: Invoked by the surviving astronauts and cosmonauts, to force a second mission to Mars to bring them home.
- Not Quite Dead: Aleida goes to Margo's office after the bombing and doesn't find her. The piano, where she was last shown playing, is gone, leaving Aleida and the audience to assume she's dead. Then the Time Skip shows that she is still alive in 2003, and living in the Soviet Union.
- Only in It for the Money: None of Dev's employees join him when they realize that leaving Helios will mean pay cuts and losing their stock options. Justified, as it's clear they'd be walking away from a lot of money.
- Someone to Remember Him By: The youngest Baldwin and the offspring of Alexei is born. The last thing in Mars orbit to remind of his father - that and his modified space-suit that brought Kelly to Phoenix.
- "Shaggy Dog" Story: Retroactively all the shenanigans Helios, NASA and the Soviets got up to to beat each other to the title "first on Mars" were for naught, as we learn in this episode. They could have spared themselves a lot of grief and complications, had they known about it earlier.
- Shout-Out:
- The episode borrows many plot elements of The Martian, particularly:
- Colonel Lee is alone on Mars for months, without any communication with his country and no one aware he even survived.
- NASA needs to cut enough weight from the MSAM to enter orbit. Once in space, Kelly goes the rest of the way to the Phoenix on an MMU.
- The remaining crews prepare themselves to spend at least two years alone on Mars, so that a future NASA mission will recover them. Will even points out that they can use homegrown foods to stretch out their rationing.
- The song at the end of the episode after the Time Skip? "Everything in its Right Place", by Radiohead.
- Colonel Lee draws a smiley face in the dust and starts giggling uncontrollably to demonstrate his Sanity Slippage. In Star Trek: The Next Generation, Picard did the same thing with a frozen cloud of exploding warp core to show that the paradox-of-the-week was affecting his mind.
- The episode borrows many plot elements of The Martian, particularly:
- Stay with Me Until I Die: In the aftermath of the bombing, Jimmy finds Karen in the rubble and stays with her until she passes from her injuries.
- Stunned Silence: Mission Control's reaction when the crews at Happy Valley choose to stay on Mars to give Kelly the best chance of making it to Phoenix, and essentially holding themselves hostage to force NASA to send Sojourner 2.Margo: Get me the president.
- Suicide Mission: It is very unclear whether the North Korean mission was planned with any intention of getting the cosmonauts back alive, and it doesn't look like their spacecraft would be able to do it.note However, given there was a loaded gun in the tiny capsule that had to fit two cosmonauts, their supplies for at least the trip there and a stay on Mars - plus fuel - it is pretty likely that all members of the North Korean Mars expedition dying on Mars or en route was considered an acceptable outcome by the leadership of North Korea.
- Surprisingly Realistic Outcome:
- Not surprisingly, coming out as gay (especially in this alternate 1995) causes virtually the entire Republican party to turn on Ellen, pushing for her to resign or be impeached.
- Dev tries to get the Helios staff to join him in forming a new company that will lead the development of a colony on Mars. Then Karen points out that they will all suffer a pay cut and lose their extensive stock options, causing them to bail on Dev. To Dev losing a few billions might be chump change - but his employees have families and mortgages and all other kinds of payments to make and losing hundreds of thousands if not millions of dollars - plus what had up to that point been a stable and well-respected gig in a growing industry - is just not an option for most of them - let alone something to do on a whim after hearing a Rousing Speech
- Danny confesses his role in the drill incident and offers to make amends by risking his life to pilot the MSAM in order to get Kelly up to the Phoenix. Ed angrily rejects the offer as he is not going to put the life of his pregnant daughter in the hands of an unstable man who is suicidal.
- Time for Plan B: The device to hack into the NASA video feed and the presence of rifles suggests that Jimmy's "friends" had a much larger plan in place than to just blow up the JSC. But then he escapes and Karen tries to alert security, leading Charles to set off the device himself.
- Time Skip: This time we end up in 2003, where Sergei is living a quiet life in suburban America while Margo is Not Quite Dead and somewhere in the USSR.
- Uncertain Doom: Bill Strausser and other Helios engineers were on their way to JSC, leaving it unclear if they were caught in the blast.
- You Have GOT to Be Kidding Me!: Pretty much the reaction of everyone from astronauts to NASA to Ellen and the Soviet Premier on how North Korea managed to beat everyone landing a man on Mars.
