“Nothing exciting ever happens on the U5,” a security officer remarks. That character clearly hasn’t watched the show. After Season 1 saw Sam Nelson (Idris Elba) inadvertently involved in a plane hijacking, Season 2 shifts the action underground, with Sam part of a hijacking of a U-Bahn subway train in Berlin, specifically on the U5 route. This time, Sam is orchestrating the hijack instead of trying to stop it. Someone else is pulling the strings, threatening to kill his ex-wife Marsha (Christine Adams) if he doesn’t comply.

Sam must get the train to the end of the line to trade the hostages’ lives for John Bailey-Brown (Ian Burfield), who organized Season 1’s Kingdom flight hijacking. Bailey-Brown killed Sam’s son Kai, so to save his ex-wife, Sam must help free the man who murdered his son.

In Season 2’s penultimate episode, we learn the hijacking is orchestrated by Robert Lang (Arsher Ali), an MI5 agent working with Stuart Atterton (Neil Maskell), who was arrested for failing to hijack a plane in Season 1. Sam thwarted him two years ago, and Atterton has been seeking revenge from prison, plotting Sam’s downfall.

In Season 2’s finale, the hijacked train full of hostages reaches its destination, allowing the handoff. While Sam safely evacuates dozens of hostages, over 100 remain. Sam hasn’t heard from Marsha, who’s still in danger, pursued by Atterton’s Cheapside Firm’s hired goons. Still, Sam allows passengers to disembark one by one.

All passengers disembark safely, but the handoff feels off: Bailey-Brown, the man meant to be freed, doesn’t know what’s happening, indicating he’s also a pawn in Lang and Atterton’s scheme. Atterton aimed to eliminate both Sam and Bailey-Brown via the hijacking, erasing traces of Season 1’s Kingdom hijacking and solidifying his control over the London-based Cheapside Firm.

Lang has the detonator and brings Bailey-Brown on the train, giving Sam a chance. Sam thinks Lang won’t blow himself up, allowing him to take down Lang and survive, along with train driver Otto (Christian Näthe). Sam confronts Bailey-Brown about killing his son Kai. Bailey-Brown laughs, saying, “Is that what he made you think?” and reveals Lang lied about killing Kai to make Sam hijack the train.

Meanwhile, Marsha slips back to the cabin, starts a controlled fire to signal the rescue helicopter—though it also draws the two attackers hired to capture her. But the helicopter arrives just in time, the attackers surrender, and Marsha escapes unharmed.

Lang exits the train, then detonates the explosive from a distance. Bailey-Brown dies in the blast, but Otto and Sam survive. Lang thinks everyone’s dead.

Lang calls Atterton, who’s in his prison cell with a smuggled phone, to report the job’s done, claiming Bailey-Brown and Sam are dead. Atterton is angry Lang called but doesn’t hang up. Atterton doesn’t know his cell is wiretapped; police have evidence of his and Lang’s involvement in the Berlin hijacking. Lang demands more money and a safe escape from Berlin, but before continuing, he finds Sam, who he thought he’d killed, chasing him.

Lang flees to the street, chased by Sam. After a brief chase, they face German police and Faber. Faber yells “It’s over” at Lang, who refuses to surrender (unlike Sam). Lang gets a call from Atterton, telling Sam “He won’t stop.” Police warn Lang they’ll shoot if he moves. Lang tries to answer the phone and is shot dead.

Atterton’s cell is raided; police take him into custody. Detective O’Farrell (Max Beesley), Marsha’s boyfriend, gleefully tells Atterton Marsha and Sam are alive, meaning his plan failed. Atterton rages at O’Farrell, but his words ring hollow after his second failed hijacking. It seems Atterton is finished, making future hijackings unlikely.

At episode’s end, Faber views Lang’s body, saying “I was blinded by obsession” for failing to spot betrayal. Sam agrees, “So was I.” Both have much to process after Berlin, especially Sam, who faced two hijackings. Season 2 ends on a hopeful note: Sam reunites with Olivia, gets his phone, learns Marsha is safe. He calls Marsha, reassures her he’s with her, and the season concludes.