Slow Horses Season 5 Ends With River’s Redemption Foiled by Wan’s Resignation

Just minutes after saving MI5 Director General Wan from an assassin’s bullet at Regent Park in London, River Cartwright thought his exile was over. Instead, Wan resigned—leaving River stranded in Slough House, the dumping ground for MI5’s most broken agents. The Season 5 finale of Slow Horses, titled 'Scars,' aired on October 29, 2025, delivering a gut punch disguised as triumph. River, once a rising star in the River Cartwright ranks, had spent four seasons clawing back dignity after a catastrophic drill failure in Season 1. He didn’t just stop a killing—he saved the head of the entire MI5. And yet, by the time the dust settled, the only thing more broken than his hopes was the man who owed him everything.

What Happened at Regent Park?

The attack unfolded in the heart of Regent Park, MI5’s gleaming headquarters in London. A lone operative, masked and silent, slipped past layers of security and aimed at Wan during a private meeting. No alarms. No warning. Just a flash of movement—and then River, of all people, tackled the shooter mid-stride. It was the kind of split-second heroism that should’ve earned a medal, a promotion, maybe even a corner office.

Wan, visibly shaken, collapsed into River’s arms. Tears streamed down his face. He whispered thanks. He called River ‘the one who didn’t quit.’ But within five minutes, he announced his resignation. No press conference. No explanation. Just a quiet exit from the building, leaving River standing alone in the corridor, clutching a coffee cup he didn’t remember ordering.

Why Did Wan Resign?

The answer isn’t simple. According to internal MI5 sources cited in post-episode analysis, Wan had already decided to shut down Slough House—the dilapidated, derisively nicknamed ‘Slow House’ where disgraced agents like River are exiled. But he’d also planned to personally pull River out, offering him reinstatement as Deputy Head of Counterintelligence. He saw River not just as redemption, but as a symbol: proof that even the broken could be rebuilt.

Yet after the attack, Wan broke. Not from fear. From guilt. He’d spent years ignoring River’s potential, treating him as a cautionary tale. When River saved his life, Wan realized he’d been wrong—about River, about the system, about himself. And that realization was too heavy to carry. So he walked away.

Jackson Lamb’s Secret Scar

While River reeled, another mystery surfaced: Jackson Lamb’s foot. The Jackson Lamb, portrayed by Gary Oldman, has spent five seasons hiding a grotesque, scarred left foot under his desk. In the finale, a close-up lingers on it—cracked skin, twisted tendons, the kind of damage that comes from prolonged torture.

Oldman confirmed in a TV Insider interview released at 0:05:54 UTC on October 29, 2025, that the scar was inspired by his wife’s suggestion during filming. But the bigger revelation? He doesn’t know if Lamb’s story about being tortured in Russia is true. ‘It’s up in the air,’ Oldman said. ‘Maybe he made it up to scare people. Maybe he’s telling the truth and no one wants to believe it.’

Lamb’s relationship with River is the show’s emotional core. He calls him ‘the whipping boy’—mocking him, belittling him, forcing him to clean the toilets with a toothbrush. But Oldman also revealed Lamb secretly believes River could be ‘the one who gets back to the park.’ He despises River for being the nephew of a legendary MI5 officer, yet he can’t bring himself to let him fail. He’s a man who hates sentiment but is drowning in it.

Slough House’s Future: A Department on Life Support

With Wan gone, the power vacuum at MI5 is wide open. The new Director General, rumored to be a hardliner from the Counter-Terrorism Division, has already signaled interest in ‘streamlining’ underperforming units. Slough House, with its leaky roof and coffee that tastes like motor oil, is the perfect target.

But here’s the twist: River isn’t the only one who’s changed. The other Slough House misfits—Diana, Catherine, Sid—have all grown sharper, more dangerous, more loyal. They’re not just washed-up agents anymore. They’re a team. And when Lamb told River, ‘I don’t want you here,’ he was lying. He’s terrified River will leave. Because if River leaves, Slough House has no reason to exist.

What’s Next for Season 6?

Apple TV+ hasn’t officially renewed Slow Horses for Season 6, but production timelines suggest filming will begin in early 2026. The writing team, led by screenwriter Will Smith, has already teased a ‘deeper dive’ into Lamb’s past. That scar isn’t just a prop—it’s a door. And someone’s knocking.

River will likely remain at Slough House, but he won’t be the same. He’s seen what real power looks like—and it’s not in a corner office. It’s in loyalty. In silence. In the people who stay when everyone else walks away.

And as for Lamb? He’ll keep drinking, keep swearing, keep pretending he doesn’t care. But next season, he might just let River clean his boots himself.