A hidden mailbag. A decades-old disappearance. And one letter that was never supposed to exist.

When renovations at Larkspur's abandoned railway depot uncover a canvas mailbag sealed inside a wall since 1988, stationery shop owner and paper conservationist Clara Whitcomb is drawn into a mystery buried for nearly forty years.

Among the undelivered letters is one addressed to Clara's late mother?and before retired postal worker Silas Boone can explain why, he is murdered.

As letters vanish and old postal ledgers reveal clues to a stolen fortune, Clara and Detective Nathan Shaw follow a fragile paper trail connected to a teenage runaway who disappeared decades ago. But someone in Larkspur is determined to keep the past buried.

Postmarked for Murder is a clean, suspenseful cozy mystery filled with small-town secrets, historical clues, an amateur sleuth, and a decades-old cold case.