‘Slow Horses’ Season 3 Ending Explained: Do River And Our Favorite MI5 Misfits Make It Out Alive?

Another season of Apple TV+‘s spectacular spy thriller, Slow Horses, wrapped on December 27, 2023. And the action-packed finale found the Slough House crew caught in several epic shootouts, conducting a Home Alone-style takedown complete with booby traps, and racking up largest body count of the series.

Based on Real Tigers, the third installment in Mick Herron’s beloved book series, Slow Horses Season 3 follows disgraced MI5 agents Jackson Lamb (Gary Oldman), River Cartwright (Jack Lowden), Louisa Guy (Rosalind Eleazar), Roddy Ho (Christopher Chung), Shirley Dander (Aimee-Ffion Edwards), and Marcus Longridge (Kadiff Kirwan) on a dire quest to save their kidnapped colleague Catherine Standish (Saskia Reeves). As they race to bring Standish back home, the group learns that her captor, Sean Donovan (Sope Dirisu), is seeking a confidential file called “Footprints,” which contains classified government secrets that his girlfriend Alison (Katherine Waterston) planned to expose — before she was murdered! When Donovan opens up the Slow Horses’ eyes to MI5 corruption at the highest level, rules are broken, loyalties are tested, and relationship dynamics seriously shift.

The end of Season 3’s penultimate episode leaves viewers questioning the fate of the Slow Horses, particularly River, who finds himself in the middle of an explosion in the records facility. Does he make it out alive? Can the team save Standish (and themselves)? And is the “Footprints” file retrieved and exposed? Decider’s Slow Horses Season 3 finale recap has the answers. (And when you’re done reading, check out our interview with showrunner Will Smith for more Season 3 breakdowns and Season 4 teases.)

Slow Horses Season 3 Ending Explained: Season 3, Episode 6, “Footprints” Recap

Thankfully, the Slow Horses Season 3 finale picks up exactly where we left off. Official documents are scattered about, ash is raining down, and River is on the ground drenched in the facility’s green light as Louisa screams “You just killed an MI5 officer!” to the agents carrying out Duffy’s kill order. Donovan takes Louisa’s gun and covers her, allowing her to sprint to River, who is thankfully still kicking. Once Donovan spooks their attackers — who retreat to call for backup — the trio makes their way to what they believe is an escape hatch. After Donovan realizes he’s been shot, he gives River the file and urges him to get it out there. “This is the kind of shit we claim our enemies do. They murdered Alison to protect their reputations. Don’t let it be for nothing. Please,” he begs.

Outside the facility, Lamb is channeling his inner Kevin McCallister and rigging Standish’s hostage house with traps — from a knife wedged in a banister and chips scattered on the staircase, to a flammable front door device and a strategically placed smart mug. With help from Sarah, he plans to use Standish as bait to take down Hobbs (Chris Coghill) and Sturges (Nick Blood). And after Ho gets a whiff of danger, he quits singing car karaoke to Iron Maiden’s “Alexander the Great” to investigate.

In a masterfully edited episode, suspense builds as we cut back and forth between the two main showdowns and a ruthless facility shootout between Shirley, Marcus, and Duffy’s agents. After growing tired of dodging literal bullets, Shirley sneaks behind two attackers and draws her gun, only for it to jam, leaving the Slough House duo in an even trickier situation. As shots fly and the Slow Horses stand their ground, Duffy grows increasingly frustrated and sends more agents inside, taking them away from the hatch.

Back at the hostage house, Hobbs and Sturges fall for Lamb’s traps in an intense, unexpectedly comical spectacle that features Roddy summoning his inner Alexander the Great, commandeering a party bus, and driving it straight into the house — after the bad guys are defeated and Standish is already saved, of course. Unfortunately, things are still dicey in the facility, with River and Louisa forced to leave an injured Donovan behind and Shirley narrowly escaping death by stabbing an agent with a broken piece of Marcus’ Elton John CD. (Thank you, Sir!)

At the MI5 offices, talks between Diana (Kristin Scott Thomas) and Ingrid (Sophie Okonedo) heat up when Diana questions Duffy’s silence and reminds Ingrid she’s killing her own again. Ingrid suggests the deaths are on Diana since she set the whole thing in motion, but a glimmer in Diana’s eyes suggests she hasn’t given up on the Slow Horses just yet.

A fed-up Duffy throws a tantrum, grabs a gun, and heads into the facility himself, where the guards have just killed Donovan — but not before he took two out himself. A flashback to him and Allison in bed together sends his character off with purpose and refocuses viewers on the mission at hand. As Louisa and River find the escape hatch, Shirley overhears plans on a walkie to shoot once they emerge, so she snags Marcus’ car keys and makes a run for it while he battles Duffy. When Louisa lifts the hatch, bullets sly and they realize they’re cornered. But not for long! Shirley plows down the agents covering the hatch with Marcus’ car, rescues River and Louisa, and tosses a grenade at the agents underground. When she asks why everyone’s trying to kill them, River holds up the Footprints file and sprints to his car to get it to safety. Meanwhile, Marcus and Duffy are mercilessly duking it out in a fistfight. Duffy admits Marcus is better than him, but when he pulls out a knife it seems like the end for Marcus, until Louisa appears, bashes Duffy in the head, and says, “Guess now we’re even!”

At the MI5 office, Diana is gloating and Ingrid is spiraling. Shirley talks to Standish on the phone as she’s driving with Roddy, Sarah, and Lamb, and it sounds like she and Marcus are finally unfired! After dropping Sarah at the ER, the trio heads to a petrol station where Lamb finally explodes after listening to Standish praise Charles Partner’s values. Standish tells Lamb that Charles thought he was worthy of First Desk, respected her, and kept her on when she was struggling with alcoholism. In response, Lamb called Charles “a fucking traitor” who “spent the last 10 years of his life selling secrets to the fucking Russians.” He tells Standish that Charles only kept her on because she wasn’t alert enough to realize he was framing her for his crimes. Then she drops not one, but TWO f-bombs, and storms away on foot.

River successfully escapes the facility, file in hand, and seeks refuge at his grandfather David Cartwright’s (Jonathan Pryce) house. After reading the file — which details MI5 using an untested device that put North Korean embassy workers and tourists in the hospital — David says it’s simply a tale with no proof and that it’s best to forget about whatever happened in Morocco. River corrects him, reminding him the events took place in Istanbul and stressing the importance of details. In another emotional exchange, both men reluctantly realize David’s memory is going. And much to River’s dismay, his grandfather tosses the crucial file in the fire, claiming it’s for the best. When River leaves and gets in his car, however, we see a copy of Project Footprint sitting on the passenger seat. So what does he do with it?

We jump forward to a sunny day, where Lamb and Diana meet for their usual banter, some ice cream, and a quick debrief. She thanks him for leaking the file, ending Ingrid’s reign, and giving her the job that should have been hers from the start, but he tells her it was all River. Diana points out that Standish left, says she’s off to meet the new Home Secretary, and has a terrible mess to clean up. “It’s you in the hot seat now, Diana. No one else to blame when shit goes wrong, which it always does,” Lamb says. “I relish the challenge. Do you really think you’re happier than me at Slough House?” she asks. “Yeah I do…and I’m fucking miserable,” he replies in true Lamb fashion.

What fresh hell awaits Diana and the Slow Horses in Season 4? Stay tuned, and read Decider’s interview with showrunner Will Smith for breakdowns, teases, and more.

Slow Horses Season 3 is now streaming on Apple TV+.