Episode 1 of Slow Horses' fourth season commences with Roddy in a precarious predicament. He arrives at Chickadoo, attired and aglow for the anticipated Christmas festivities, only to find the place eerily deserted. The realization dawns that Jackson has been pulling the wool over his eyes all along; there's no festive bash in sight. Louisa's confirmation of this grim news sends Roddy packing, just as a distant explosion shakes the very fabric of London.
MI5 springs into action, swiftly pinpointing the culprit on CCTV – a suicide bomber who rammed a vehicle into a shopping center, reducing it to rubble. The rental car is traced to a phantom named Robert Winters, a 28-year-old freelance IT consultant who exists only on paper. Investigations at his purported address reveal a non-existent Winters, with neighbors oblivious to his existence. This enigmatic figure casts a long shadow, fueling speculation whether this is an isolated incident or the harbinger of a sinister campaign.
Over drinks at the pub, River and Louisa delve into this mystery, toasting to their imagined freedom from Slough House's clutches in the foreseeable future. Amidst their conversation, River's concern for his father's deteriorating mental state bubbles to the surface. David's descent into paranoia is evident, with a gun now a constant bedside companion and a recent encounter where he failed to recognize his own son for the first ten minutes. Louisa urges River to confront his father that very night.
David's paranoia deepens by the hour. Dozing off in his chair, he's jolted awake by pounding at the door. Assuming it's River, he's startled when the visitor, face obscured, rushes upstairs to the bathroom. David's gaze flits between a photo of his grandson on the mantelpiece and his shotgun before ascending the stairs. In a blur of panic and confusion, he fires, only to find himself staring at River's face, horrified by the irrevocable act he's committed.
Jackson Lamb arrives on the chaotic scene, where Emma Flyte introduces herself as Nick Duffy's successor. The grisly sight of blood-splattered bathrooms greets Lamb, who notes the panic button pressed by the kitchen table. The deceased, shot twice – once in the chest, once in the face – bears River's ID and wallet, leading Lamb to the grim conclusion that it's River himself. But in this twisted tale, nothing is ever certain.
Leaving the crime scene amidst playful jabs with Flyte, Lamb embarks on a quest to locate the now-absent David Cartwright. Behind the wheel of his car, he nibbles on a Jaffa cake, mind racing with the next steps in this labyrinthine puzzle.
In the dawn's early light, Diana makes her way to Claude's office, her presence a beacon of impending assistance. He, perched anxiously at his desk, seeks guidance for his maiden voyage into the treacherous waters of a COBRA meeting, his inexperience palpable in every tense gesture. Diana, swift and succinct, dishes out a crash course on the intricate dance of politics before delivering the gut-wrenching news of River's demise. Though the two events appear disparate, a sinister undercurrent binds them together.
Meanwhile, the shadowy figure behind the shopping center bombing surfaces, releasing a chilling video online, a macabre promise of further carnage echoing through the digital realm. The bomber's voice, cold and menacing, hints at an ominous "message from his brethren" yet to come. MI5, swift and decisive, traces the video's digital footprint to a nondescript flat, sending in armed escorts to apprehend the perpetrator.
But upon their arrival, the flat lies eerily vacant, a stark contrast to the threat it once held. The only trace of life: a solitary garment, neatly folded beside the sofa, a foreboding omen. Amidst the barrenness, a passport, its details matching the fugitive's, serves as a fleeting clue.
As forensic experts cautiously pull back the curtains, they unwittingly trigger a trap, revealing the flat to be a booby-trapped labyrinth. Grenades, hidden in plain sight, erupt in a deafening blast, reducing the sanctuary to rubble. Diana, stunned and resolute, orders an immediate evacuation of the entire block, her voice ringing with urgency.
Claude, caught in the midst of the chaos, is a picture of fear and uncertainty. Diana, her gaze stern yet compassionate, urges him to confront his fears and embrace his newfound responsibilities. This man, she muses, might yet prove to be a hindrance, his timidity a potential liability in the turbulent days ahead.
At Slough House, an atmosphere of disbelief hangs heavy as Roddy, with a casual air, claims River's computer, its hard drive potentially holding the key to unraveling the mystery of his fate. Amidst the tumult, Lamb arrives at Catherine's doorstep, his news a stark contrast to the despair that had enveloped them all.
With a delicate balance of empathy and revelation, Lamb informs Catherine that River, contrary to all belief, is still very much alive. His car, parked outside her home, a tangible reminder of his resilience. And as if fate had orchestrated a bizarre reunion, David finds himself unwittingly sharing Catherine's sanctuary, while River, alive and well, speeds away in a taxi, his destination seemingly France—a glimmer of hope amidst the chaos.
