'For All Mankind' season 4 episode 10 review: A season finale that saves the best for last

"For All Mankind"'s fourth season opened with an episode named " Glasnost ", and closes with another word synonymous with Mikail Gorbachev's reforms of the former Soviet Union: "Perestroika." It translates as "restructuring" and that feels entirely appropriate for an instalment that – after a season of transition – feels like it's well and truly altered the trajectory of the show.

Let's not pretend "For All Mankind" is still alternative history – it's now full on science fiction. Running at close to 80 minutes, "Perestroika" is a lengthy affair, but also the best episode of the season. It's a powerful mix of interplanetary action, redemption, revenge, and ingenuity in mission control – indeed, scientists in Houston are just as pivotal to the episode's gripping climax as the people in spacesuits.

And, while you could argue that the outcome of the episode is rarely in doubt, few could have predicted the ingenious route "Perestroika" takes to get there. Related: 'For All Mankind' season 4 episode 9 review: The race for Goldilocks is well and truly on North Korean Lieutenant Colonel Lee (C.

S. Lee) is concerned about the health status of Commander Cho (Charles Kim), having incapacitated his boss last week. Gerardo Ortiz Niño (Salvador Chacon) is worried that Cho could identify him if they take him to med bay, but Ed Baldwin (Joel Kinnaman) overrules him, arguing that they don't have a choice.

Lee offers to escort him there and claim his injuries were the result of an accident with a cargo loader – a remarkably similar excuse to the hydraulic lifter "malfunction" that supposedly incapacitated Petros in episode 6 . If Dr. Dima (Goran Ivanovski) wasn't such close friends with Ed and Lee, he'd be getting suspicious by now… In a "Two Months Earlier" flashback, Helios staffer Frank Tuttle (Kurt Quinn) spots an incongruous metal pipe embedded in the Martian surface.

On investigation he discovers it's a marker for a handgun buried in the sand. He takes the weapon back to his quarters, cleans it up, and hides it in his locker. It's a very literal representation of Chekhov's Gun , because you just know the weapon is going to have a pivotal role to play before the episode is done.

In the meantime, some of "For All Mankind"'s sizeable soundtrack budget is spent on The Rolling Stones' "Out of Time" – an apt choice, seeing as it's just over two hours until Ranger 2 needs to make the crucial engine burn that will send the Goldilocks asteroid back to Earth .

On Ranger's command deck, wannabe asteroid heister Samantha Massey (Tyner Rushing) checks to see that the illicit discriminator unit she installed is still functioning, under the watchful eye of ever suspicious Happy Valley XO Palmer James (Myk Watford). Meanwhile, Helios boss, fellow conspirator, and now spy Dev Ayesa (Edi Gathegi) looks on as Ops Com makes final preparations, tapping out covert Morse code messages to the "Ghost Ops" base on Sub Level 4.

In fact, we'd go as far as saying she's actively worried, and concerned enough about Roscosmos defector Sergei Nikulov (Piotr Adamczyk) – who isn't answering his phone – to ask Aleida Rosales (Coral Peña) to check in on him. After all, with Irina in town, Houston really isn't safe – this is confirmed when the motel receptionist tells Aleida that this "real sweet guy" killed himself in his room.

Elsewhere on the base, CIA and KGB sleeper agents Mike Bishop (Billy Lush) and Timur Arilov (Nikita Bogolyubov) are taking their interrogation of Miles Dale (Toby Kebbell) to morally dubious extremes. As they increase the carbon dioxide to levels that make the victim feel like their head is going to explode, there are obvious parallels with the "enhanced" interrogation techniques used by the Bush administration in the real early 21st century – challenging themes that "For All Mankind" co creator Ronald D.

Moore explored (to brilliant effect) in his earlier sci fi classic, "Battlestar Galactica" (arguably one of the best sci fi TV shows of all time ). Even though Miles is pushed so hard he vomits on Timur's shoe, he stays quiet – but his plea that "I just want to see my family" may just prove to be his undoing.

Sleeping in her office – some things never change – Margo Madison (Wrenn Schmidt) is woken by a call to meet NASA boss Eli Hobson (Daniel Stern). It turns out that Roscosmos supremo Irina Morozova (Svetlana Efremova) has made a surprise trip to Houston to ensure she has a front row seat for the final stages of the Goldilocks mission, and – it seems – to accompany Margo back to Star City.

Margo is… not delighted. On Happy Valley, Bishop briefs base commander Danielle Poole (Krys Marshall) that Miles is refusing to talk. Dani's gut is convinced Miles is involved somehow, however. With the stakes getting higher, she orders that all non mission essential personnel be confined to quarters.

The Helios staffers are, unsurprisingly, annoyed by the declaration of martial law, and don't go quietly. But, as the searches of their possessions continue, one of Happy Valley's makeshift troops finds the (not yet smoking) gun, and discreetly pockets it for himself. As expected, Bishop plays the family card, showing Miles photos of his wife, Amanda, receiving Martian contraband.

This evidence that could help put her away for five years, leaving their kids in the care of Child Protective Services. Miles' pleas to leave them out of it fall on unsympathetic ears, and he eventually divulges that the conspirators are on Sub Level 4. With just 54 minutes to go until showtime, Dev overhears Bishop telling Dani he's found the asteroid thieves – just enough time to tap out a "mayday" message to his team.

By the time Dani and the troops find the makeshift "Ghost Ops" facility, most of the plotters have escaped to the North Korean compound, wallowing in the news that their audacious plan has failed. Gerardo is left behind and quickly finds himself with Bishop's baton pushed against his throat.

"That's enough!" shouts Dani, realizing that Bishop's extreme techniques might not align with her own values. At NASA, Eli is bewildered that anyone might want to sabotage a mission undertaken for the good of all mankind, but astronaut turned administrator Will Tyler (Robert Bailey Jr.) assures him that Ranger's discriminator is now back under Happy Valley control.

Revised trajectory calculations are sent to Mars , but Aleida has weightier matters to deal with. In a perfectly judged, powerful scene, she tells Margo what's happened to Sergei. It plays out through a window in near silence, voices muffled to the point of inaudibility as Wrenn Schmidt works her way through several stages of grief in a matter of seconds.

Margo isn't going to take this lying down, and storms up to Irina, shouting, "What did you do?" and "Don't fking try to handle me," as Irina coldly attempts to calm her. Margo gradually realizes this isn't the time or place, but this clearly isn't over.

As the long awaited burn gets underway, the conspirators assess their diminishing options. Ed spots a transmitter that could be their salvation, as the M 7 treaty stipulates that North Korea must have a private channel with officers on board the ship. If they can use it to make contact with Sam, she can manually disconnect the engines from the flight deck, meaning the only person in control of the burn would be Dev.

But, in the finest traditions of " Star Wars ", " Star Trek " and pretty much every action movie ever made, the crucial controls are outside the ship, meaning Sam will have to undertake a spacewalk on a vessel whose engines are firing at full blast. As Sam embarks on her risky EVA in a North Korean suit, the stakes become immediately clear when the panel she removes from the fuselage floats into space, where it's instantly vaporized by Ranger's engines.

Conveniently, it turns out that the override controls are big, chunky, and easy to follow. Unfortunately, the crucial lever is also spring loaded, meaning it returns to its original position as soon as it's released – Ranger was clearly designed by TV scriptwriters rather than NASA engineers.

The solution involves Sam removing her tether to secure the switch in place – dangerous at the best of times, but even more so when Palmer's suiting up to foil your plans. On Happy Valley, Bishop has worked out that Ed, Dev, and co. are holed up in the North Korean compound, and waiting for Washington's approval to make a highly controversial incursion.

Dani realizes this is a bad idea and raises her old lunar roommate Ed on comms – "Hi Bob!" – to try and talk him down. As she argues that Earth is still their home, he counters that his family and his future are all on Mars, and that he won't let the red planet wither and die when Goldilocks returns to Earth.

Lee echoes his sentiments. Back at the Molly Cobb Space Center, space engineer Seth Razack (Ely Henry) suggests a way to ensure Sam's extra vehicular activities fail. By uploading a shutdown command to turn off the gas to the engines, they can ensure the burn ends on time, whatever happens on Mars.

But with radio signals taking minutes to reach the red planet – a helpful narrative device here – the clock is well and truly ticking. Looking on from the observation room, Margo reminisces to Aleida about her mentor, rocket scientist Wernher von Braun, who tried to justify his work for the Nazis with the statement: "Progress is never free.

There is always a cost." While Von Braun made it seem like he had no option but to follow orders, Margo reasons there's always a choice, and echoes Ed, Dev, and Sergei's hypothesis that NASA, Roscosmos, and the rest of the M7 will lose interest in Mars if Goldilocks makes it back to Earth.

"We can't let them throw away everything we've built." Margo writes some new code that, when inserted into NASA's new command, will prevent Ranger's engines from obeying the shutdown command – it's double and triple and maybe quadruple crossing via the medium of software design.

With the NASA code being written on the fly, however, Margo says she'll have to input her amendments just before uplink. "Let's do it," says Aleida. Overruling Margo's objections, Aleida volunteers to be the one to uplink the code, reasoning that there will be too many eyes on Margo.

In space, no one can hear their superior officer approaching, and Palmer knocks Sam away from the Ranger controls. It's a full on race against time as Seth and Margo/Aleida's signals are winging their way towards Mars, and Sam is left hanging off the back of the ship with one hand. As the clock counts down towards zero, Palmer does what he can to cut through the tether, but with seconds to go, Sam goes full Ellen Ripley à la ' Alien ' and pushes him off the ship, leaving him swinging perilously close to the (still) burning engines.

As the camera pulls away, we're treated to a truly glorious shot of Ranger moored to the Goldilocks asteroid, heading in the direction of Mars. With a bit of unexpected help from Margo and Aleida, the conspirators have succeeded. The elated hugs in the North Korean compound are in stark contrast to the utter dejection in Happy Valley Ops Com, and – a few minutes later thanks to time lag – NASA mission control.

Seth realizes that an additional command has been added to his code, and Irina instantly fingers Aleida as the perpetrator. Aleida rightly points out that Irina doesn't have the astrophysics knowledge required to make such a strong accusation. "Perhaps not," comes Irina's chilling reply, "but I can tell when someone is lying, as you are now." As Eli begs Aleida to tell him it isn't true, Margo steps forward to take the blame.

"You shouldn't have done that, Margo," says Irina. "There will be consequences." And, indeed, there are, as Margo has her diplomatic immunity withdrawn by the Soviet Union and is instantly arrested by the FBI. There's still time for Aleida to run over and give Margo a hug, in one of the most moving moments of the season.

"It'll be okay, Aleida," Margo assures her. There's still unfinished business up on Mars, where Bishop has gotten his authorization to venture into North Korea. It's the first Dani's heard about it, and she tries to stop him, but Bishop isn't interested in her protests.

"Due respect," he says – with, it has to be said, minimal respect – "but my orders come directly from the DoD and they supersede your command." As Timur continues to interrogate Miles and Gerardo, former black market kingpin Ilya (Dimiter D. Marinov) leads the rescue of his former protégé.

Miles then rallies his Helios co workers, telling them, "It's time we remind them who really runs this base." Bishop's troops soon find they're fighting a battle on two fronts, with North Korea on one side and an army of angry contractors on the other. There's a sense of tragic inevitability when that aforementioned gun makes its way into the skirmish, and – after an ugly mêlée – Dani finds herself on the wrong end of a bullet.

It's enough to end the fighting, everyone looking on as they wait to see if their commander is okay. — 'For All Mankind' Season 4 hopes to get audiences excited about space — 'For All Mankind' needs recruits for Mars in 4th season on Apple TV+ (video) — New collectible pin buttons depict 'For All Mankind' space mission patches Fortunately, it's not long before we see her safe and sound back on Earth, meeting her new grandchild for the first time.

The closing montage – soundtracked by a very "Star Trek" speech from Margo about the notion of justice – also shows Lee reunited with his wife on Mars, and Irina having her office searched by KGB heavies. Maybe Margo got her revenge after all… The episode closes with a triumphant Dev staring out over the Korolev crater, as M83's "Midnight City" (which U.K.

viewers might recognize as the theme to reality show "Made in Chelsea") starts to play, and the show makes its customary end of season time jump – this time to 2012. With mining work well underway at the Kuznetsov Station (named after heroic Soviet cosmonaut Grigory Kuznetsov), it looks like Dev and co.'s bold plan has come to fruition.

There are still plenty of questions to be answered, however. Will Mars declare independence from Earth? What will happen to the conspirators? Will Miles and the others bring their families out to Mars? And will there still be room for original characters Ed, Margo, and Dani half a (fictional) decade after they first appeared in the "For All Mankind" story? If the show does return – a fifth season is yet to be confirmed by Apple – it seems set to travel even further from its roots in the Apollo era, more sci fi than it's ever been before..