So it’s finally over. Three seasons, 28 episodes, and a truckload of peril. It’s satisfying to be able to write that Lost in Space got to conclude its story, as that’s not something the original series ever managed. The 1960s version lasted three seasons, too, but was retired before its makers had a chance to finish off the Robinsons’ tale.

Luckily, that’s not the case this time. "From the beginning, we've always viewed this particular story of the Robinsons as a trilogy," showrunner Zack Estrin said last year. "A three-part epic family adventure with a clear beginning, middle and end.”

Whether it really was always the case that Lost in Space would climax with its third season, there’s little to suggest that its makers have had to rush to tie things up. It’s been a largely successful season and its final episode, ‘Trust’, packs a decent emotional punch. Sure, a few characters feel desperately underserved, but that’s a problem inherent for a show with a cast as overspilling as this one.

The episode kicks off with Alpha Centauri already under attack from the robots, while Smith is stalking the hospital with the aim of murdering her old nemesis, Captain Radic, who’s there in a medically-induced coma. That’s the plan, anyway, until Robot interrupts her with a “Help, Dr Smith”. “Help who?” she asks, but it becomes clear Robot means her as he reaches out to take the syringe from her.

Meanwhile, Will, Penny and Judy have been sent away to the planet’s copper mine, for safety, supposedly. But the convoy of chariots is stopped when an army of robots land in front of them. It’s then that Will figures out what the invaders are after – it’s the engine from SAR’s ship, which the robots plan to use as a bomb.

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An incapacitated Will (he’s still recovering from his heart transplant) tells Penny she must keep the engine away from the robots. “It’s got to be you,” he tells his sister. “You’re smart, brave, and you’re stronger than you think.”

SAR in Lost in Space season 3 (Netflix)
SAR in Lost in Space season 3 (Netflix)

Penny saves an injured robot, names it Sally (“You look like a Sally,” she tells it, though it really doesn’t) and faces up to SAR and his army, with a gaggle of newly emancipated robots behind them.

Will travels on the Jupiter 2 with Dr Smith, but his new artificial heart begins to fail him. Robot saves Will, apparently destroying itself in the process. Later, Dr Smith confides in Will that the Robot saved her when she was about “to do something you can’t come back from”.

John and Maureen face the remaining robots, including SAR, but fail to kill him. At the last minute, the others arrive, including Will, whom SAR attempts to stab. “He knew you’d go for my heart again,” Robinson Jr says, and with that, Robot’s data is transferred, killing SAR and reviving Robot in the process.

The final moments of the episode show life after that dramatic showdown. Maureen and Don are spending most of their time, it seems, in orbit, constructing a new ship to replace the Resolute, while John is just chilling on Alpha Centauri (“they say soldiers, more than anyone else, appreciate the value of peace,” Penny tells us in a voiceover). Judy is working in the medical facility now and Dr Smith is finally in custody after delivering a confession to a now-awake Radic. The episode's final scene takes place around the Robinsons’ dinner table, with the family (plus Don) tucking in to a hearty meal while Will tells them of his plan to explore the galaxy, with Robot by his side.

Given the sheer weight of characters in this show, it’s only to be expected that some feel neglected in this final episode. Judy, so prominent in the early part of this season, has little to do here, while Don, although allowed a few hero moments, is still Mr Comic Relief. In fact, Will aside, it’s Penny who has the greatest arc here, having come the farthest from the timid, bookish creature we first met back in season one.

Apart from Penny adding ‘Of Chapter One’ after ‘The End’ in her book, this appears to be the final full stop on the Lost in Space story. Not that there’s no spin-off potential here - that tantalising closing shot of Will and Robot looking out over an exotic alien world suggests there’s mileage in a smaller Robinson story, should Netflix ever decide to greenlight Chapter Two. Heck, we’d even take a Don West sitcom sequel.

Even if there is no spin-off, let’s applaud Lost in Space for actually getting the Robinsons home. Neither the original series, nor the 1998 movie managed that.

Lost in Space season three is streaming on Netflix now. For more, check out our dedicated Sci-Fi page or our full TV Guide.