There are a thousand stories in New York's scenic Thousand Islands, and Bayside Books co-owner Shelby Cox stocks them all. But lately, the Blye Island bookseller's life is more about the investigation than inventory. True-crime writer Savannah Page caps off two successful signings at Bayside Books with a night in Blye Castle. She's there to research Joe Cabana, a colorful Prohibition-era mobster who owned the castle—until he was found dead in the island Grotto.

But crime becomes all too true for Savannah. Her body turns up the next morning in a secret passage at the bottom of the stairs. The last thing Shelby Cox wants is to sleuth another murder, but she's intrigued about how a killer could have reached the island after hours. She's not at a lack for suspects either. It could have been anyone, from Savannah's fiancé Liam Kennelly, who argued with her the evening before, to island caretaker Matthew Kessler, recently cleared of his wife's murder. Can Shelby keep regular store hours, elude the police chief, and assemble the clues into a hard-bound case without getting permanently shelved?