Episode 3 of Season 4 of "Slow Horses" kicks off with a haunting melody of chiming bells, jolting River awake within the confines of his trapped domicile. His initial despair soon gives way to a glimmer of hope as a rescuer materializes, armed with a shotgun, proclaiming that someone seeks his presence. However, River's relief is short-lived; his phone, a vital link to the outside world, is nowhere to be found.
Meanwhile, David is consumed by a frenzy of guilt, convinced that he's ended River's life. He confides in Catherine, his voice laced with urgency, warning of impending doom and the looming threat of a bomb. Catherine, adopting the role of a soothing secretary, strives to quell his fears, but David's remorse refuses to be silenced.
Jackson Lamb's return to the office is marred by an unexpected visitor, prompting him to swiftly dispatch Louisa with the task of relocating David. Stepping into his sanctuary, he finds Emma Flynne waiting, her presence foreboding. The revelation that the deceased body is not River's, as confirmed by meticulous bloodwork, only intensifies the tension. Emma intends to bring River in for obstruction, and with handcuffs binding his wrists, he's led away. Yet, on the stairway, Jackson seizes an opportunity, using David as leverage in a calculated bargain with Emma. For now, Lamb holds the reins.
Emma's subsequent visit to Catherine's apartment unfolds as a cunning trap, her mission thwarted as she frantically scours the premises, realizing she's been outmaneuvered. David's absence is a telling sign that Catherine has orchestrated a switch, concealing him in a so-called "safehouse"—a clever ruse that transpires to be her neighbor's abode. However, upon arriving with Louisa, they're confronted with an ominous sight: the backdoor ajar, and David vanished into thin air.
Back at the heart of MI5, Claude orchestrates a clandestine operation, enlisting Giti's expertise behind Diana's back. His mission: to delve into the dusty archives of cold cases, a forbidden endeavor Diana has staunchly opposed, in search of any straggling agents lurking in the shadows. As Molly and Claude clash over this unauthorized maneuver, Giti delves into the files, her fingers tracing the secrets of the past.
River's gaze finally converges on his visitor, revealing a woman by the name of Natasha, unbeknownst to him, the very mother of Winters, a moniker cloaking the man's true identity—Bertrand. Without hesitation, River spills the beans on David's fate, earning him a ticket to freedom, which he staunchly refuses to accept. Armed with a photograph and a determination to prevent further carnage, he demands to know the identity of Bertrand's siblings.
Enter Victor, a formidable figure wielding a shotgun, who is not only Natasha's cousin but also a man with a turbulent past. Frank Harkness, seemingly the head of this complex web, may very well be shrouded by an alias of his own. Victor's violent confrontation with Frank, stemming from Frank's attempt on his life, and the revelation that the bomber, Yves, was a victim of childhood cruelties, adds layers to Natasha's stoic acceptance of his actions. Her stay at the mansion further unravels a mystery, as it transpires that another woman's hand adorned the bedroom with its paintings.
Bertrand's reputation precedes him, marred by accusations of assaulting a young girl, casting a shadow over his name in the community. As the unruly mob outside rages on, Victor's efforts to quell the chaos prove futile, forcing River to flee for his life.
Meanwhile, Jackson uncovers a clue: Sam Chapman, David's bagman, traveled to France in the early 90s, while David himself remains absent from the records. Arranging a meeting with Chapman, Jackson soon realizes that Frank has Chapman under surveillance, marking him as the next target, with Jackson hot on his heels.
Chapman's awareness of his tailing intensifies the stakes, as he calls upon Jackson for confirmation. Marcus and Shirley are summoned into action, but Marcus' recent sale of his firearm to settle gambling debts leaves him less than ideal for the task at hand. The stage is set for a tense confrontation, where every move could be their last.
The tail, relentless in its pursuit, trails Chapman, only to be disrupted by Marcus' clumsy entrance, who promptly collides with a glass window with a resounding thud, shattering it into pieces. Shirley, swift in her actions, secures a jagged shard of glass and hurries after, but the elusive tail has already gained a significant lead.
Within the confines of a dimly lit garage, Marcus and Shirley engage in a fierce battle with their adversary. Despite their combined efforts, he proves to be a formidable opponent, effortlessly overpowering them both. Just as all seems lost, Jackson arrives on the scene, commandeering a taxi as a weapon and sending their foe flying with a bone-jarring impact. However, the cunning foe manages to slip away, leaving Jackson empty-handed and frustrated at the missed opportunity for interrogation.
