Ward takes us back to the world of DC Connie Childs, DI Matthews and DI Francis Sadler, who is on holiday for five days while Connie attempts to hold the fort back at Bampton's CID headquarters. Connie's investigative skills are piqued by the sudden death of Nell Colley, an unmarried spinster. Nell had been ill with worsening cardiac arrythmia, though her neighbor reports that she'd had been feeling slightly better in the days before her death. At first there's nothing suspicious about the circumstances, so Connie labels Nell's case "no further action." Yet she can't quite shake the tug of disquiet. Apparently, Nell was writing a memoir about "the dark secrets" of Bampton.
Meanwhile, longtime resident Mina Kemp--an avid canoeist and gardener--is attempting to make her way east, away from the lights of Bampton to the Topley trail, an empty towpath on the outskirts of the village. Here lies the old Bampton Station, a stone bridge and "the Cutting," an old tunnel where the train used to through. Mina is disturbed by the blackness of the tunnel and its ripe smell that occasionally wafts towards her. She remembers a railway reference to the cuttings, but her knowledge of trains is so scant that she may be imagining it.
The dark spaces of tunnels and the canal bridge comprise an essential aspect of Ward's mystery that creates a sense of the past, but not one that is forlornly forgotten. A sense of oppression strafes through the story's events from 1957 to 2017. When Mina receives the word of a change in her mother's condition, she rushes to the hospital. The infection combined with cancer is causing Hilary to have a series of fever dreams in which she has seen a woman called Valerie. As Hilary struggles to make herself articulate, Mina asks her for more information on Valerie, the person Mina is supposed to be looking for: "If she's been to see you, I'll find her for you and we'll clear up the confusion; she's obviously not dead."
Sadler returns to work just in time to meet Connie's new colleague, the charming DC Peter Dahl. The team are soon investigating the death of another woman, Ingrid Neale. After Connie and Peter interview Ingrid's sister, Monica, Connie notes the oddity that both women were found sitting upright on the sofa. Both had chronic conditions: a heart problem in Nell's case and asthma in Ingrid's. Connie knows there's a link. It's just too much coincidence that they're looking into two deaths and then find a link with a third.
In Ward's twisted plot, the killer remains elusive. But there are other mysteries to solve, sometimes masking the one at the novel's center--Mina's hunt for Valerie, who Hilary is convinced is visiting her in hospital. But there's also the mystery behind Catherine Hallows, who has been volunteering at the hospital. Catherine is asked by an anonymous figure to prevent Mina from digging into the past. Full of her mother's fears, Mina is plagued by a sense of dread. What could her mother have been involved in?
Because Ward keeps the action at a low key even at critical junctures, the novel functions less as a thriller than an astute character study, and occasionally a critique of Bampton's sensibilities. As images of Mina's past jostle for attention, Sadler's police investigation proceeds along its own course. The Cutting at the embankment must be important, because Hilary always avoided the railway and refused to venture near the walking trail. In the middle of her heartache, Mina tries to uncover something that has been deliberately left in Hilary's past. Her mother's words come back to haunt her, with Mina adrift in her grief. When Sadler and the team investigate Hilary's death, Mina realizes that Emily Fenn, her mother's old acquaintance, lied about knowing "the Valerie in the photo" of a long-disbanded group of friends. Mina eventually learns that those who we believe to be trustworthy may not be, and those who find themselves anew may be fooling themselves.
A cold brutality runs beneath Bampton, a shared conspiracy gone horribly wrong. From an affair with a married man to a long-dead childish prank, the cold brutality of murder is enmeshed with the history of a group of schoolgirls going way back to 1957. Connie and Sadler are in top form as they realize that the more you think you know about the inhabitants of the village, the more they will fool you.