From the New York Times bestselling author of The Woman in Cabin 10 and The It Girl comes an unforgettable new thriller.

On Halloween night 1990, bestselling novelist Elinor Thorne was killed at her remote medieval manor house, struck down by a masked assailant who fled into the night. Her seven-year-old granddaughter Margot could only watch as her beloved grandmother's life ebbed away. The killer was never found.

Now, more than thirty years later, the estate is to be sold, and as the family gathers at Stonelees House for the last time, Margot tells them why she's here: to find out the truth behind her grandmother's murder. The police may have suspected local teenagers, and the press may be baffled, but the villagers have always believed that Margot's cousin Dido did it.

Dido, just sixteen years old at the time of the murder, was a prime suspect along with her boyfriend, local outcast Ruan Pearce. The Thorne family rallied to protect their own—but was it at the cost of the truth?

As the days tick down to the sale of Stonelees House, bitter secrets begin to surface, along with memories that threaten everything Margot thought she knew about her family and childhood. But Margot is determined to clear her cousin's name, or prove her guilt, no matter who stands in her way.