Spook Street

The novel opens with a suicide bombing at Westacres, a shopping center on London's western fringe. Dozens of teenagers gather at the mall's central fountain for a flash mob, dancing to music from a ghetto-blaster. At 3:04 p.m., an adult man unbuttons his overcoat among the dancers and detonates a bomb, killing upwards of forty people and reducing the building to charred rubble.

Two days later, Slough House stirs to life. Slough House is the Intelligence Service's dumping ground for disgraced agents, known as "slow horses," housed in shabby offices on Aldersgate Street. Its head, Jackson Lamb, a slovenly and manipulative spymaster, has been largely absent since September. His replacement for the departed Catherine Standish is Moira Tregorian, a prim former office manager from Regent's Park, the Service's headquarters. The remaining slow horses include River Cartwright; Louisa Guy; Marcus Longridge, whose gambling addiction is destroying his family; Shirley Dander, who attends court-ordered anger management sessions; Roderick Ho, the team's self-aggrandizing tech specialist; and JK Coe, a former officer in the Service's psychological evaluation section who copes with past trauma by silently miming piano recitals at his desk.

After work, River confides in Louisa about his eighty-four-year-old grandfather, David Cartwright, a former near-head of MI5, Britain's domestic intelligence service, whom River calls "the O.B." (Old Bastard). The O.B. lives alone in Kent and is experiencing worsening memory loss and paranoia. He interprets ordinary neighborhood activity as surveillance by enemy agents he calls "stoats" and keeps a gun in the house, no longer stored in a safe. River's deepest fear is that someone will come to the door and the old man will shoot them.

That evening, a stranger rings the O.B.'s doorbell claiming to be River. Suspicious, the O.B. lets him in but retrieves his gun and shoots the man dead. River arrives to find blood on the walls and a dead man who closely resembles him but lacks his distinctive mole. The body carries a passport in the name of Adam Lockhead, a Eurostar ticket, and a café receipt from Le Ciel Bleu in the French village of Angevin. Fearing the Service itself may have ordered the hit, River fires a second shot into the dead man's face to obscure identification, plants his own ID on the body, and drives the confused O.B. to Catherine Standish's London flat. He then takes the passport and ticket to retrace the assassin's journey to France.

Lamb is summoned to the Cartwright house, where he meets Emma Flyte, the new Head Dog, or leader of the Service's internal security division. Though he notices the victim lacks River's mole, Lamb deliberately identifies the body as River Cartwright, adhering to the principle that one never blows a joe's, or field agent's, cover. At Slough House, the team initially believes River is dead until Coe points out that Lamb's text mentioned only "Cartwright's body." Lamb later confirms River is alive and instructs the team to find whatever connects David Cartwright to France.

Meanwhile, Claude Whelan, the newly appointed First Desk, or head of Regent's Park, prepares for a Cabinet Office Briefing Rooms (COBRA) meeting with the Prime Minister. The bomber has been identified as Robert Winters. Whelan's deputy, Diana Taverner, privately discovers that Winters's passport is a "cold body," a fully legitimate identity created by the Service's now-defunct wardrobe department, the unit responsible for building long-term false identities during the Cold War. Three such identities remain unaccounted for: Winters, Paul Wayne, and Adam Lockhead. Taverner argues that if the Service's connection to Westacres becomes public, it will destroy the intelligence services, and she moves to suppress the information.

In France, River finds Les Arbres, the house where Lockhead lived, reduced to ruin by a deliberate fire set three nights earlier, the same day its residents departed. A hunter named Victor tells him the house sheltered around twenty people for over two decades, including Russians, an American, and various Europeans, with children who grew up there. Victor directs River to Natasha Reverde, a woman with ties to Les Arbres. Natasha tells River she bore a son named Patrice by a Russian man living at Les Arbres in 1990. The compound was led by an American named Frank. She shows River photographs of the children, including Frank's son Bertrand and a boy named Yves, whom she describes as someone who viewed other people as insects.

Back in London, Lamb sends Marcus and Louisa to collect Bad Sam Chapman, a former Head Dog who served as Cartwright's bodyguard on trips to France in the early 1990s. Patrice, now operating under the Paul Wayne identity, is also hunting Chapman. In a garage confrontation, Patrice breaks Chapman's knee with a crowbar before Marcus crashes a commandeered taxi through the gates, allowing them to rescue Chapman.

At Slough House, Coe explains "Project Cuckoo," a Cold War concept in which artificial environments were used to raise agents who could pass as enemy nationals. A former Central Intelligence Agency (CIA) operative named Frank Harkness proposed adapting Cuckoo to raise children as prototype suicide bombers. Regent's Park rejected the proposal after learning Harkness had been burned by the CIA. But when Lamb pushes the O.B. for answers, the old man breaks down and says one word: "Isobel," his daughter and River's mother. The truth emerges: Frank and Isobel had a relationship. Cartwright, then aiming for First Desk, secretly funded Frank's project in exchange for Frank staying away from Isobel. Les Arbres was Cuckoo in action, and the Westacres bomber, Yves, was one of Frank's indoctrinated children who went rogue.

River returns via Eurostar and is intercepted by Flyte, but Patrice rams their car and forces River at gunpoint to the Embankment near Blackfriars Bridge. Frank Harkness waits there and reveals himself as River's biological father. When River refuses Frank's attempt to recruit him, Frank throws him over the wall into the Thames. Following Frank's orders, Patrice enters Slough House and kills Marcus at his desk and Chapman on the kitchen landing. Lamb, returning with a bottle of whisky, hurls it into Patrice's temple as Patrice kicks through a barricaded door, and the team subdues him.

At the river, Louisa jumps into the Thames and pulls River to the surface. Flyte chases Frank under Blackfriars Bridge and forces his surrender at gunpoint, backed by armed police on the bridge above. Back at Slough House, Catherine talks Shirley out of executing the bound Patrice, arguing it would haunt her forever. Shirley lowers the gun into Coe's hand. Coe immediately shoots Patrice three times in the chest.

The following evening, Whelan visits Lamb and reveals that Frank cooperated during interrogation, claiming his dry-run operations across European cities had tightened security until Yves went rogue at Westacres. The Service has released Frank to prevent the full story from becoming public; he slipped his surveillance within minutes. Lamb blackmails Whelan into authorizing a ten-year death-in-service payment for Marcus's family, double the standard, and a medical retirement for Moira. He holds leverage: Moira once served as duty officer the night the Metropolitan Police picked Whelan up for soliciting from his car. After Whelan leaves, Catherine surveys the damage. Lamb pours her a whisky. She raises the glass, breathes it in, then sets it down untouched. Lamb pours her portion into his own glass and makes his way out through the empty building into the night.