'For All Mankind' season 4 episode 7 review: Teases a spectacular end of season run

"Crossing the Line" may be the shortest episode of the season so far, but that doesn't mean it's short on incident. As tensions at Happy Valley escalate and the Helios workers' strike brings the base to a standstill, both sides go to extreme measures to turn the dispute in their favor — with literally explosive consequences.

The shockwaves of exiled NASA head Margo Madison's (Wrenn Schmidt) decision to go public on her defection to the U.S.S.R. are still being felt, particularly by former protégée Aleida Rosales (Coral Peña), who's far from happy about her old boss's unlikely resurrection. Meanwhile, Helios CEO Dev Ayesa (Edi Gathegi) — a peripheral player for much of the season — makes arguably the boldest (and undoubtedly the most ludicrous) move in "For All Mankind" history.

Indeed, after a run of episodes that's prioritized talk over action, the pieces are in place for a spectacular run to the season finale. Life on Mars isn't easy right now, but for the next three weeks the red planet is set to be the bright center of the universe.

Related: 'For All Mankind' season 4 episode 1 review: Lots of moving parts but light on plot

Spoilers ahead for "For All Mankind" season 4 episode 7: "Crossing the Line"

The Helios workers' strike threatened in last week's episode "Leningrad" has now reached its seventh day, and — from dirty laundry littering the corridors to maintenance jobs left undone — the industrial action has left its mark on Happy Valley. In a fiery meeting between Mars's top brass and the Helios staffers (led by Samantha Massey (Tyner Rushing) and Ed Baldwin (Joel Kinnaman)), XO Palmer James (Myk Watford) does his best to lay down the law, explaining that Helios is a "non-union shop" and they're all in violation of their contracts, so "every penny lost will be docked from your pay."

Sam challenges the company to "fire us," pointing out that nothing will get done on Happy Valley without them. Ed stokes the fire further, talking about his colleagues putting "their asses on the line." This goes down like a lead balloon with base commander Dani Poole (Krys Marshall), who scathingly reminds Ed that — until recently — he was bemoaning those same colleagues' lack of qualifications for living on another planet.

The Helios workers know they'll be out of a job if the Goldilocks asteroid heads for Earth, and frankly, Dani's suggestion that Helios could pay for them to be retrained isn't going to cut it. So, Sam lays down an ultimatum: if their paymasters want clean habitation, cargo unloaded, and for the cryocenter to get back to producing liquid argon, the powers-that-be need to start making some concessions. Dani — who's used to operating in a military-style chain of command — argues that she's gone out of her way to address their concerns, but they're running out of time to get the fuel they need to capture the lucrative asteroid. With the clock ticking — and a potential Kobayashi Maru-style no-win scenario on the cards — who will budge first?

Back on Earth, NASA boss Eli Hobson (who dealt with a few strikes during his time as CEO of Chrysler) discusses the industrial action with his Roscosmos counterpart, Irina Morozova (Svetlana Efremova). Both of the bureaucrats are under pressure from their respective presidents to get things moving, but Irina's approach to the workers' "tantrum" is — as you'd expect — more hardline. Although Eli is skeptical about ordering unqualified astronauts and cosmonauts to restart the cryocenter, Irina counters his concerns with the argument that they're all engineers. "If Helios will not help us," she says, "we'll have to help ourselves."

With some strikers losing their stomach for a drawn-out feud, Sam and Ed tell them they need to stay the course. (It's worth noting that, after mounting his mini, North Korea-backed coup to take over Happy Valley's black market, Miles Dale (Toby Kebbell) is very quiet this week.) They're roused further by news that NASA and Roscosmos are planning on restarting the cryocenter's generators themselves. "They're trying to f**k us," comes the rallying cry from Ed. "Are we going to let that happen?"

The question gets a rather eloquent response when Palmer and his team discover that all of Happy Valley's spacesuits have gone AWOL, and are now lying outside on the Martian surface, tantalizingly out of reach. The strikers have also used rovers to block the airlocks to the fuel plant. Even Palmer has to admit it's a clever play.

With the cryocenter too far away for improvised pressure suits — we all saw what happened to Gordo and Tracy Stevens in the season two finale when they took a D.I.Y. approach to life support — it's time to get creative. Palmer suggests going under rather than over, which means belly crawling through a maintenance pipe leading to the fuel plant — after it's been drained of some rather unpleasant gray water from the base's composting tanks.

Over in Moscow, recently outed defector Margo is no longer being ignored on the Roscosmos campus. She's also taken a seat at Irina's top table, emboldened to mock a Soviet bigwig who thinks Helios is simply serving Gore's interests. "I have met Dev Ayesa," she says, "and I can promise you he cares more about his own interests than America's." Irina reveals that the U.S.S.R.'s intelligence backs up her assessment.

After further discussion of the Goldilocks capture mission, Irina asks Margo to stay behind. She drops a surprising — if dramatically convenient — bombshell: Margo is to be dispatched (with full diplomatic immunity) to Houston to act as Roscosmos's liaison with NASA, and President Korzhenko won't take no for an answer.

If you were wondering what kind of reception Margo is likely to get back home, a show on conservative T.V. network Eagle News provides the litmus test. Helios's resident asteroid capture expert Aleida Rosales believes she's been invited on the program to talk about bringing Goldilocks back to Earth, but host Zoey Chase (Thea Andrews) would much rather discuss "Moscow Margo," aka the most wanted woman in America.

As Aleida and family watch the broadcast in their living room, it's instantly apparent that things didn't go well. Instead, the interview ended with Aleida storming off the set amid a flurry of curse words — if nothing else her son, Javier (Santiago Veizaga), is very impressed. Speaking with her husband, Vic (Jorge Diaz) in the aftermath, she recalls the experience of meeting Margo, and how the elation she felt on learning her old mentor was alive quickly turned into wishing she was dead again. Vic tells her she can't just sit back and let Margo return to NASA: "Maybe take a cue from the folks up on Mars. Push back."

Dev, Kelly (Cynthy Wu), and her son Alex (Ezrah Lin) make Mars-fall. There's an emotional reunion for Kelly and Dani, but the base commander quickly diverts to intercept Dev — let's face it, they really need to talk. Ed arrives late to the party to meet his grandson for the first time, but the boy is nervous about coming face-to-face with his intimidating "Poppy" — and that's before he's got to know Happy Valley's most awkward resident.

Dev is in awe of the view outside his window, but Dani wastes little time in reminding him that it's his Helios workers who are causing the crisis and that "they've got legitimate grievances against your company." That remark riles the Helios CEO, who says he's "considering my options," before ending the conversation with a very cold "thank you." Dani isn't going to give him the last word, however, and offers a curt reminder that on Mars she's the one in charge. Dani 1, Dev 0.

Alex gets an exam from Dima (Goran Ivanovski), the doctor who assisted in his outer space birth. It's a lovely scene, in which Dima recalls working (and playing games) with Alex's late dad, Alexei. And, as minor as the exchange is, his opinion that Mars' low gravity is — as Kelly suspected — beneficial to Alex's respiratory condition will surely have very big ramifications later in the season.

If only living with Poppy was so easy. When we first met Ed in season one, he was taking a tough love approach to parenting with his late son, Shane, and he still thinks he knows best. Even though grandson Alex says he doesn't want parmesan cheese on his pasta, Ed sprinkles some on his dinner anyway. When Kelly challenges his actions, Ed says he was just trying to broaden the boy's horizons.

He also asks her to cut him some slack — he's fighting for a cause, after all — and suggests she join him on the picket line. Kelly tells him he's being short-sighted, and that Aleida has done something amazing in her Goldilocks work, but that simply opens the door for Ed to express the true motives behind his fight with management. He's concerned that, if the asteroid heads for Earth, Happy Valley will turn into a forgotten scientific backwater and never be able to grow into the thriving colony it could be. We've known since the start of the season that Ed has no intention of going home, and with Alex's health seemingly improved on Mars, Kelly is clearly going to have some big decisions to make.

Palmer goes full "Shawshank" and leads a team into the "longest 800 meters on Mars" pipe – given the echoes of a scene from "Aliens," it can't be an accident that one of his associates is named Bishop. Getting the generators restarted is not going to be as easy as they thought, however, because one of Ed's team has removed a primary gas flow regulator from the facility, "just in case." Have the strikers just crossed a line into sabotage territory?

Palmer's team improvise a workaround, and the generators fire up. Yet the success is short-lived, as we quickly hear the ominous rattle of a malfunctioning system. "Tell them to shut it down," orders Dani as numerous warning lights turn red, but it's too late, and part of the cryocenter explodes.

Aleida storms into Eli's office at NASA, demanding that Margo be arrested as soon as she steps on American soil. Eli says the decision is above his paygrade, and that Moscow is insisting that Margo co-chair the Goldilocks capture discussions. "If we're going to pull this off, we need the best people from all over the world," he says. Aleida says she can't work with Margo, but before the debate can continue, Eli's assistant interrupts to tell them there's been an accident at Happy Valley.

It's all hands on deck at Happy Valley's medical center, which is briefly transformed into a full-on Martian E.R. Palmer has come off relatively unscathed, but others have suffered serious burns. When NASA assesses the situation in a Molly Cobb Space Center boardroom, they confirm there's been one fatality (so far), four more badly injured (two of those in critical condition), and that Dima is doing his best to keep them alive. Sadly, as astronaut-turned-administrator Will Tyler (Robert Bailey Jr.) puts it, "it's not looking good."

CIA Deputy Director Bob Burks (David Bowe) tells Eli that the strikers have "dramatically escalated" the situation. He says that the CIA "knows for a fact" that the Soviets have at least one KGB asset in Happy Valley, and reveals that the Americans also have "assets" up there, with access to "non-lethal weapons." It's a shock to Eli, who's not delighted at the prospect of martial law being declared on Mars. Bob argues that these "terrorist attacks" — something of an exaggeration, perhaps — require extreme measures, but Eli shuts him down without hesitation.

Unfortunately, sending up a security detail as they did for the 1983 lunar uprising (as seen in season two) isn't an option because of the timescales involved. Will does come up with an alternative though — they can deputize people on Happy Valley with "adequate" military training.

"This isn't why any of us came up here," says Dani, addressing her unlikely new security force, "but it's our duty now to ensure the security of this base and the safety of this crew. We need to find those responsible for this explosion." The hunt for that smoking gun — or smoking primary gas flow regulator — is now well and truly on.

With Jennings dead and even Sam believing things have gone too far, Dev makes a belated intervention in the Helios dispute. He tells the strikers he respects them for the way they've negotiated, and for standing their ground. But his address also contains the hard truth that, unless they get the dispute sorted today, Goldilocks will be lost and they'll all have failed in their goals. He also reminds them that the nations of Earth will never send the asteroid to Mars because it's not in their financial interests.

He is, however, prepared to put his (vast pot of) money where his mouth is, offering improved pension contributions, amnesty for actions conducted during the strike, and massive bonuses for the first hundred people to accept his terms. Ed and Sam say he's trying to buy them off (which he clearly is), but the offer is too good for most of them to refuse.

As Aleida watches on her computer, Margo arrives at NASA — under a sizeable security escort — for what's surely going to rank among the most fraught workplace reunions in history. But the episode saves its real kicker for the end.

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Dev may be the last person Ed wants to see in his quarters, but the Helios CEO has a plan and he needs Ed's help to see it through. "We both want the same thing," Dev says. "To never go back [to Earth]."

Ed points out that Dev's intervention in the strike has effectively killed any aspirations for a Martian colony stone dead, but Dev counters that the strike was as much a blessing as an inconvenience. He now knows that some Helios staffers are committed enough to the Martian cause to support his Bond villain-level delusions of grandeur: "Do you want to help me steal an asteroid?" he asks.

In a season that hasn't always hit the heights of its predecessors, Dev's seemingly ridiculously plan sets up the final three episodes beautifully. Plausibility may be an increasingly minor concern in a show that started out as an alternative history of the Apollo program (which grew out of the space race), but in terms of unashamed sci-fi action, this is set to be huge.

New episodes of "For All Mankind" debut on Apple TV Plus on Fridays.