Years ago, bookseller and mystery aficionado Malcolm Kershaw compiled a list of the genre’s most unsolvable murders, those that are almost impossible to crack - which he titled "Eight Perfect Murders". But no one is more surprised than Mal, now the owner of the Old Devils Bookstore in Boston, when an FBI agent comes knocking on his door one snowy day in February. She’s looking for information about a series of unsolved murders that look eerily similar to the killings on Mal’s old list. And the FBI agent isn’t the only one interested in this bookseller.

The story opens with the apparently accidental drowning of a sixth form student in the Norfolk countryside. As a matter of routine, or so it seems, the case passes across the desk of Detective Sergeant Smith, recently returned to work after an internal investigation into another case that has led to tensions between officers at Kings Lake police headquarters. As an ex-DCI, Smith could have retired by now, and it is clear that some of his superiors wish that he would do so.

A week's holiday in a luxurious hotel is just what Scotland Yard's Superintendent Duncan Kincaid needs. But his vacation ends dramatically with the discovery of a dead body in the whirlpool bath. Despite a suspicious lack of cooperation from the local constabulary, Kincaid's keen sense of duty won't allow him to ignore the heinous crime, impelling him to send for his enthusiastic young assistant, Sergeant Gemma James. But the stakes are raised significantly when a second murder occurs....

Clare Cassidy is no stranger to murder. A high school English teacher specializing in the Gothic writer R. M. Holland, she teaches a course on it every year. But when one of Clare’s colleagues and closest friends is found dead, with a line from R. M. Holland’s most famous story, “The Stranger”, left by her body, Clare is horrified to see her life collide with the story lines of her favorite literature.

Fiona, Sue, and Daisy, three retired ladies who volunteer at the local charity shop, Dogs Need Nice Homes, can’t believe their favorite customer is dead. Eighty-six-year-old Sarah Brown was found murdered in her hallway by her delivery man, a domino clutched in her hand—with a name scratched on it. When another person is found dead with a domino in their hand, and with the police making no progress, the ladies will need to help unmask a serial killer. At least they have Fiona’s scruffy-haired terrier cross to assist them.