The New Couple

The novel opens with a disorienting prologue: an unnamed woman is dragged from a truck to a remote building near the coast, pushed down steps into an underground chamber, and chained to the wall. As her eyes adjust, she sees a human-shaped form nearby and assumes it is a dead body, until a faint croak reveals that another person is alive and imprisoned alongside her.

The story shifts to Jane Headley, a classroom assistant living at number 5 Sycamore Gardens, a crescent of mid-Victorian houses in South London. Her husband, Fergus Headley, is a professor of economics at the London School of Economics (LSE); their grown children are away, and the marriage has grown distant. Jane learns from her neighbor Danielle Salter that number 12 has been sold to Prodomus, a charity that raffles prestige properties, and that the draw has been won by Richard and Stephanie Hamlin, parents of nine-month-old Poppy.

Jane watches the Hamlins' chaotic move-in with suspicion. Two nearly identical men in hoodies unload black bin bags from a dirty pickup truck; one introduces himself as Richard, the other as his brother Elliott. The couple has no baby equipment, and Stephanie is flat and unresponsive. Despite her initial coldness, Stephanie soon begins asking Jane to babysit Poppy for extended, unexplained absences, always insisting the baby stay at number 5. Each time, she returns hours late, pale and distressed.

At a neighborhood barbecue, Richard attends alone and flirts openly with Irina Semenova, a model engaged to hedge fund manager Michael Kovacic. Jane follows Stephanie by train to Ebbsfleet International in North Kent but loses her at the station. She later witnesses Richard and Irina having sex in a neighbor's garden. When Richard confronts Jane on the street, warning her to stop spying, she confides in her friend Trish Oldenshaw, whose boyfriend, retired police officer Tony Waddesdon, advises Jane to stay away but also to investigate. A police database check on "Richard Hamlin" comes back clean.

Jane visits the accountancy firm where Richard claims to have worked; a colleague named Tom Chen confirms that a Richard Hamlin did work there. However, neighbor Xavier Moreno tells Jane that Richard could not answer basic accounting questions. Number 12 is listed for sale, cash only. On Fergus's phone, Jane spots a missed call from "S," deepening her suspicion that Fergus is entangled with the Hamlins. During a tense holiday in Suffolk, Fergus drinks heavily and orders Jane to stop her preoccupation with the couple.

Using a spare key to a neighbor's house, Jane secretly records a conversation between Richard and Irina in which he pressures her to leave Michael so they can access her prenuptial agreement, worth two and a half million pounds per child. Tom Chen listens to the recording and declares with certainty that the voice is not Richard Hamlin's: The real Hamlin has a strong Welsh accent. Shortly afterward, the couple vanish from number 12.

The novel's second section shifts to Keren Stockley's perspective, beginning months earlier. Keren, a nursery worker at Stepping Stones, lives with her boyfriend Liam Devenish, a warehouse supervisor with a severe gambling addiction. Liam's twin brother, Lance, is a frequent presence. After being evicted for unpaid rent, the couple enter the Prodomus draw and lose. Keren recognizes the winners: Stephanie is a parent at her nursery. Liam notices that both couples bear a striking physical resemblance and proposes they impersonate the Hamlins, take the house, and sell it. Keren, desperate, agrees.

Posing as a Prodomus representative, Liam lures the real Hamlins into a car, and Lance overpowers them. The brothers chain the couple in an underground chamber at Eastmeade Fort, a derelict artillery installation on the Kent marshes near Gravesend. Keren removes Poppy from the nursery and moves into number 12, assuming Stephanie's identity. She manages the Hamlins' digital communications to prevent suspicion while Liam roams freely.

Keren spots Fergus kissing a young woman on his doorstep. Liam tells her to identify the woman; Keren later goes on her own initiative to Fergus's office at the LSE and photographs the name on the woman's mail pigeonhole: Selina Permeti. Liam uses this as leverage. On the night he confronts Jane on the street, he also threatens Fergus: If Fergus does not silence Jane, Liam will expose the affair. Desperate, Fergus begins gaslighting Jane, dismissing her concerns and physically pulling her away from number 12.

Keren secretly visits the Hamlins at the fort, bringing food and supplies but refusing to release them. Meanwhile, Liam begins an affair with Irina, growing obsessed with her wealth. As the deception crumbles, Stephanie's real sister tracks down the address from Prodomus and visits during a house viewing. Keren takes Poppy and the dog to her half-sister Siobhan's house in Chelmsford, claiming the baby is hers. She confronts Liam about his affair and demands her share of the money, but he is dismissive. She packs to leave.

Liam decides the Hamlins must die, since Keren's visits mean Stephanie can identify them by name. He sends Lance to execute the couple, but Lance cannot pull the trigger. Liam goes himself. The Hamlins ambush him in the dark; both manage to flee, but Liam shoots Richard in the flank and recaptures Stephanie. He re-chains Stephanie and leaves Richard bleeding on the marshes. A news report later confirms that a body with a gunshot wound has been found nearby: Richard has died. Liam summons Irina to the Savoy hotel, but she ends the affair, having agreed to give Michael another child. Liam refuses to accept the breakup.

Returning to Jane's perspective, the revelations converge. At a birthday barbecue, she tells Tony everything; he urges her to contact the police. That evening, Fergus confesses his affair with Selina and admits that Liam blackmailed him, explaining why Fergus had been gaslighting Jane and dismissing her suspicions. At the Stepping Stones nursery, a staff member identifies the imposters as Keren Stockley and Liam Devenish and confirms the baby is genuinely Poppy Hamlin. Jane and Fergus report to Detective Constable Lester Boateng at Brixton Police Station, but the response is slow.

Jane texts Irina to warn her but walks into a trap: Liam has seized Irina's phone and holds her captive at number 17. He forces Jane at gunpoint to the marshes and chains her in the fort, connecting directly to the prologue. The other prisoner is Stephanie, emaciated after nearly four months of captivity. She tells Jane that Liam shot Richard during an escape attempt and that Richard fled but never returned. Jane realizes the body on the marshes is almost certainly Richard but does not share this with Stephanie.

The next morning, Keren appears at the fort, retreating in panic at first. She returns, tearfully explaining that Liam used her and was never going to share the money. Jane persuades Keren that helping them is her best option, since the police already know everything. Keren knocks a padlock key from a high ledge using an empty bottle, frees both women, and the three escape into daylight.

On the coastal path, Liam and Lance intercept them with pistols, but a police helicopter appears overhead and armed officers converge. Irina had freed herself from her restraints and alerted Trish and Fergus, who contacted the authorities. Keren charges at Liam; his gun discharges, hitting her in the chest before officers swarm the scene.

An epilogue set the following February reveals the aftermath. Keren's wound proves superficial; she pleads guilty to lesser charges and receives eight months in prison. Liam, unrepentant, and Lance face trial on charges including murder, kidnapping, and fraud, with expected sentences exceeding twenty years. Stephanie is reunited with Poppy and moves to Yorkshire; the voided house sale proceeds are directed to her. Jane and Fergus sell number 5 and move to Bath, where Fergus has accepted a new position and Jane plans to pursue a full law degree, inspired by her experience with the criminal justice system. She is willing to try repairing the marriage but remains uncertain whether she can truly forgive Fergus.