Beyond the Sea is the third episode of Black Mirror season 6 and is the longest of the bunch, clocking in at 1 hour and 20 minutes.
Following on from Joan is Awful and Loch Henry, the third episode is also very different in tone as it follows two astronauts in an alternate 1969, who are taking on a six-year mission in space.
The episode follows Cliff (Aaron Paul) and David (Josh Hartnett) as they're forced to spend time away from their respective families, but are able to return home thanks to state-of-the-art technology known as Replicas.
This allows them to spend time back on Earth, with their consciousness existing in a synthetic body for short periods of time. It's a way of boosting morale among astronauts and their families.
However, this is Black Mirror we're talking about, so things soon take a turn for the worse and the sinister nature of using Replicas is explored.
Here's what happened in the heartbreaking episode Beyond the Sea...
What happened in Beyond the Sea?
This feature-length episode kicks off with a horrific tragedy after astronaut David is forced to watch while his family is brutally murdered in front of him by a group of intruders who are against Replicas.
David's life is ruined in minutes and his Replica is also destroyed on Earth meaning it's unusable. He's now completely doomed to exist in space for the next few years until the mission is complete with no way of returning to Earth as himself.
It's a bleak scenario that prompts Cliff and his wife Lana (Kate Mara) to take pity on him, suggesting that the two astronauts share Cliff's Replica so that David can also enjoy some fresh air and time away from space.
The offer is gratefully received, and David spends his first day in Cliff's Replica exploring the forest and talking to Lana, who tries her best to console him when he breaks down in tears over the reality of the situation.
Back on the ship, Cliff realizes that David has sketched his home and compliments his art style. David asks if he can return to Earth on a regular basis so he can paint a canvas for them as a sort of thank-you gift.
Cliff reluctantly agrees and David starts spending more and more time with Lana. Over time, he starts to develop feelings for her and realizes that Cliff has not been particularly intimate with Lana, with the two of them barely touching each other whenever he's on Earth.
After a few visits, David does eventually make a move on Lana who is angry with him for betraying her trust. She accuses him of "confusing her" since he's using her husband's body and is equally as horrified when David hits her son to discipline him, as she believes he has crossed a line since he's not her husband.
Cliff allows David to come back one last time, so Lana leaves the house for the day with her son. While David is using Cliff's Replica, Cliff finds drawings in his bunker. They're all of Lana and many of them are of her naked and posing. Cliff thinks they're having an affair because David claimed he can only draw from memory.
When David returns to the ship, Cliff confronts him about the drawings and he insists it's "just a fantasy" and nothing happened. Cliff punches David and tells him to leave his wife alone, and David hits back by accusing Cliff of not appreciating his family.
Cliff returns to Earth in his Replica and confronts Lana who echoes what David said, assuring him that nothing happened and there's no affair, although she "misses him" and "wishes he had touched her". This serves as a reality check for Cliff who realizes how distant he's been, and the two embrace.
When Cliff comes back to the ship, David apologizes but Cliff gets aggressive with him claiming Lana "feels sick" when he's around and repeatedly reminds him that Lana is his and he'll never get to have her, trying to intimidate him.
We flash forward and while Cliff is on Earth in his Replica, David fakes an emergency alert to lure him back to the ship where he claims one of the external coolant pipes needs looking at.
David suits up and heads outside the ship after removing items like his watch, his dog tag and crucially, the key that activates his Replica, for safekeeping.
However, he soon realizes that nothing is wrong, and reports back to David to tell him that everything's clear. He doesn't get a reply and bangs on the door frantically, as he's locked out in space.
The door light turns green and David claims he was in the bathroom, handing Cliff his belongings back from the tray. However his key was missing and David wordlessly pulls it out of his pocket, handing it to him.
Cliff panics and rushes to his room where he plugs in the key allowing him to access his Replica. Back on Earth, he looks down to see the Replica's hands bloodied, and there are bloodstains all over the house.
Horrified, he descends the stairs slowly and realizes that David had brutally murdered his family in a similar way to his own. It's not shown on screen but we do see him breaking down into tears in horror.
Cliff returns to the ship in tears where he sees David waiting for him. Neither of them speak but David nods, kicking out the chair and gesturing for Cliff to sit down. The two are now forced to complete the rest of their mission with the knowledge that neither of them have families to go home to.
