TL;DR: Slow Horses Season 6 Episode 2 deepens its conspiracy, gives Jackson Lamb plenty of room to cause chaos and brings Sid Baker back with a major reveal that deserved to remain a surprise.

Slow Horses has always been ridiculously good at making espionage look both terrifyingly dangerous and deeply embarrassing. Season 6’s second episode, “Daddy Issues,” leans hard into that contradiction, pushing several mysteries forward while still finding time for Jackson Lamb to verbally destroy anyone unlucky enough to wander into his orbit. After a strong opener, Episode 2 feels more confident and more complicated, with multiple threads beginning to connect around Slough House. And then comes that ending — a reveal that should have landed like a grenade, had Apple not already pulled the pin in the Season 6 trailer.

Sid Baker is back, and that changes everything

Yes, Sidonie Baker is alive. Olivia Cooke’s Sid makes her long-awaited return in the closing moments of “Daddy Issues,” appearing at River Cartwright’s late grandfather’s house and immediately creating an impressive number of questions with very little screen time. Where has she been? Why stay hidden? And what exactly does she want with River?

Bringing Sid back is a smart move because her disappearance has remained one of those unresolved pieces of Slow Horses history that never completely went away. Unfortunately, the execution loses some of its power because her Season 6 appearance was revealed before the episode aired. Without that knowledge, the final moments could have been one of the season’s biggest WTF reveals. Instead, I spent part of the episode waiting for the inevitable. It still works narratively, but the surprise factor has effectively been nerfed before we even got to play the level.

Slough House is being erased one agent at a time

Sid’s return provides the episode’s biggest headline, but the darker development is what happens to Moira. Joanna Scanlan’s former Slough House administrator becomes another target of the mysterious pair played by Kyle Soller and MyAnna Buring, reinforcing the disturbing idea that somebody is systematically cleaning up people connected to Slough House.

What makes the killers interesting isn’t simply their efficiency. Slow Horses gives them small behavioural details that make them feel unsettlingly human rather than turning them into anonymous spy-thriller assassins. There is a strange casualness surrounding their violence, while their own uncertainty over whether they are working from the correct list introduces an important wrinkle. If the people being killed aren’t necessarily the intended targets, then this operation may be far messier than it initially appears. Coe and Shirley, meanwhile, begin following the trail after investigating their dead colleague’s houseboat, and their partnership continues to be unexpectedly effective.

Jackson Lamb remains the king of weaponised sarcasm

Gary Oldman once again gets some of the episode’s best material. Lamb can turn almost any conversation into psychological warfare, whether he is snapping at River or tormenting Molly at the Park archives. What continues to impress me is that Slow Horses never treats these jokes as something separate from the thriller. The comedy exists inside the tension rather than stopping it.

That balance is especially important after creator Will Smith’s departure following Season 5. Two episodes into Season 6, the personality of the series remains reassuringly intact. Roddy talking about Bitcoin, River casually imagining violence against him, and Lamb firing insults across rooms could easily become sitcom material in another show, yet here those moments make Slough House feel like an actual dysfunctional workplace populated by people who happen to deal with national security. The stakes are serious; the employees remain absolute disasters. Perfectly balanced, as all things should be.

Frank Harkness brings River’s family problems back into the conspiracy

The episode also pulls Frank Harkness deeper into the central mystery. Hugo Weaving’s character appears connected to the removal of Slough House records from the Park, having commissioned the Dog responsible for obtaining the files before killing him. That alone would be enough to complicate River’s already spectacularly unhealthy family tree, but the existence of a witness makes the situation even more dangerous.

This is where “Daddy Issues” earns its title without needing to scream about it. River is chasing a mystery that increasingly seems connected to his own history, while Frank remains one of the most dangerous pieces on the board. Slow Horses works best when professional espionage and personal baggage become impossible to separate, and Season 6 is clearly steering River toward exactly that collision. The danger isn’t merely somebody stealing files or eliminating former agents anymore; it’s that River may be walking directly into something tied to his father.

Diana Taverner finally looks uncomfortable

Kristin Scott Thomas also gets an interesting shift this week. Diana Taverner has spent much of Slow Horses behaving like someone who already knows where every body is buried — occasionally because she helped put it there. Seeing her struggling with the consequences of accepting money from Peter Judd therefore adds another layer to the season.

Her forced interview with Talkpoint puts her in a position we rarely see: reacting rather than controlling. The political and financial pressure surrounding her new role as First Chair creates a different kind of threat from the killings surrounding Slough House, but the two storylines complement each other. Everyone appears to be compromised by something, whether it’s family, money, old operations or buried institutional secrets. Season 6 is rapidly turning MI5 into a giant Jenga tower where practically everyone has already removed one block too many.

Episode 2 has a lot of plates spinning

The biggest concern after “Daddy Issues” is simply how much Slow Horses now has to resolve. Sid is back. Former Slough House personnel are being murdered. Coe and Shirley are investigating. Frank Harkness is involved with stolen records. River is digging into the mystery. Diana has her own political nightmare developing. And we are only two episodes into another compact season.

For now, the series handles that density remarkably well. The episode moves quickly without feeling like it is dumping exposition on the audience, and its humour prevents the expanding conspiracy from becoming exhausting. But there is a risk here: every new mystery creates another question that eventually needs a satisfying answer. Slow Horses has built itself a wonderfully tangled web; now Season 6 needs enough runway to untangle it without turning the final episodes into a frantic mission briefing.

Verdict

“Daddy Issues” is another strong Slow Horses episode, combining murder, institutional conspiracy, dysfunctional family history and Jackson Lamb’s seemingly infinite supply of insults into a tightly controlled hour of television. Sid Baker’s return immediately gives Season 6 another fascinating direction, even if Apple’s decision to reveal Olivia Cooke’s comeback beforehand steals some of the moment’s impact.

More importantly, the episode proves that the series still understands exactly what makes it special. The espionage is gripping because the characters are messy, funny and frequently awful at behaving like normal human beings. There are now a lot of mysteries competing for attention, and the shortened runway makes me slightly nervous about how cleanly they can all be resolved. But after two episodes, Slow Horses Season 6 is moving fast, making me laugh and giving River Cartwright yet another reason to consider changing his surname.