When Penny Dahl calls the Finders Keepers detective agency hoping for help locating her missing daughter, Holly is reluctant to accept the case. Her partner, Pete, has Covid. Her (very complicated) mother has just died. And Holly is meant to be on leave. But something in Penny Dahl's desperate voice makes it impossible for Holly to turn her down. Mere blocks from where Bonnie Dahl disappeared live Professors Rodney and Emily Harris. They are the picture of bourgeois respectability: married octogenarians, devoted to each other, and semi-retired lifelong academics. But they are harbouring an unholy secret in the basement of their well-kept, book-lined home, one that may be related to Bonnie's disappearance. And it will prove nearly impossible to discover what they are up to: they are savvy, they are patient, and they are ruthless.