Slow Horses is back, and if you’ve been following the five seasons so far, you’re probably already emotionally committed to this unlikely group of friends, colleagues, and spies. Yes, our screw-ups are almost incompetent (almost, because they’ve solved some very complex cases), undeniably traumatized, frustrated, and yet deeply committed.

After taking us through secrets about his own family — ones even he didn’t know — River isn’t the catalyst of the drama this time, nor is he directly connected to it, which by itself makes this season’s opening episode feel very different. In the present day, the violent attack that sets a new conspiracy in motion — and forces Jackson Lamb and his team out of their uneasy “peace” — is particularly disturbing because it doesn’t feel far-fetched at all.

How Is the Massacre Politically Linked?

Adapted from Mick Herron’s London Rules, this season dives into political conspiracies and violent terrorist attacks, something that becomes clear right from the premiere. The title of the book is even quoted by Jackson Lamb in a great line explaining that “London Rules” means “every man for himself” — or, more bluntly, “cover your own ass.”

The episode opens on a gray London morning at the Abbotsfield Shopping Centre. The shops have just opened, and a middle-aged man is setting up his stall to campaign for one of the candidates in the upcoming mayoral elections. In a residential building overlooking the square, another man eats his breakfast quietly. Nothing seems suspicious — until we notice a misogynistic poster on his wall.

Moments later, he hears the honk of a van in the back alley and goes downstairs to check. A white van is waiting for him. He opens the back door, takes out a bag, and walks to the square. He sits down on a bench. The man campaigning tries to make small talk, but the younger man suddenly stands up, pulls an assault rifle from the bag, and opens fire — first on the campaigner, then on everyone in the square. Panic erupts. By the end, the report confirms 11 dead and several wounded.

What’s even more unsettling is what follows: a second shooter — a sniper from a nearby tower — kills the gunman with a single shot to the head, quickly packs up his gear, and flees. He gets into the same white van that supplied the gun, suggesting the entire operation was premeditated — including the shooter’s own execution.

What Are the Slough House Agents Up To?

Right after the attack, we see Roddy Ho walking to the office, blasting loud music in his headphones. He is almost run over by a white van, but Shirley Dander saves him at the last moment. To her, this is no coincidence — someone is targeting the Slough House agents.

At the office, we catch up with how each character is coping with the trauma from last season:

• River Cartwright is still processing the fact that his father was a terrorist and that he had to stop him from destroying London. The only person he speaks of fondly is his grandfather, David, who now lives in a retirement home because of his worsening dementia.
• Catherine Standish remains calm and steady, loyal to the rules and to her care for her colleagues.
• Shirley is the most shaken — Marcus’ death, her close friend and sobriety partner, has left her paranoid. She’s convinced the van that nearly hit Roddy was a deliberate attack, but no one takes her seriously — except Lamb, who keeps his concern to himself.

The Political Connection

Emma Flyte, head of MI5’s tactical unit, investigates the shooter’s apartment. The attacker is identified as Rob Trew, and inside his flat, she finds a picture of him with conservative politician Dennis Gimball, along with several of Gimball’s books. Gimball is known for his anti-immigration rhetoric and promises to “clean up” Britain. Trew’s first victim was a campaigner for Gimball’s rival, Zafar Jaffrey, a popular leader among minorities.

Everything points to political motivation, but the fact that Trew was executed by an accomplice raises suspicions of a setup. Perhaps someone is trying to frame Gimball to ruin his chances in the election.

Rob Trew’s Past

Rob had no criminal record, lived in isolation, and was estranged from his family. He was active on an online forum called The Unseen, where resentful men shared misogynistic and xenophobic grievances. Trew was encouraged by another user, Sniper762, who not only egged him on but seemingly provided weapons and money. This user’s data was wiped from the site before the attack — but the name is telling: Trew was killed with a 7.62-caliber bullet, confirming the link.

River and Louisa

River tries to get closer to Louisa Guy and kisses her, but she reveals she’s taking a six-month leave — and plans never to return to Slough House. River is devastated. Louisa asks him not to contact her.

Is Roddy Really in Danger?

Shirley continues investigating the van and discovers it is identical to the one used by the sniper to escape. By the end of the episode, we learn she was right — Roddy is indeed in danger. His new girlfriend is seen sending suspicious messages, letting someone know when he returns home alone. Whether she’s part of a bigger conspiracy or just a common criminal remains to be seen — but this will become a major subplot this season.