The Sign of the Devil

In "The Final Frey & McGray Mystery," a botched grave-robbery uncovers a corpse featuring a chilling symbol, while a murder in an Edinburgh lunatic asylum connects back to the same ominous mark. Amy McGray, a notorious inmate previously convicted of murder, becomes the prime suspect, prompting her brother, Detective 'Nine-Nails' McGray, to defend her innocence. He enlists the reluctant help of his old friend, retired Inspector Ian Frey, as they navigate unexpected twists and long-hidden secrets in this thrilling conclusion to the Frey & McGray series.