Nurse Miriam Ward arrives at Abbott’s Lodge on a snowy winter night to care for the ailing Paul Abbott. But when she returns from admitting midnight visitors, she finds a stranger in her patient’s bed— and Paul Abbott murdered. Chloroformed before she can raise the alarm, Miriam awakens to find herself the chief suspect in a baffling crime. As Sheriff Guy Trenholm investigates, the mystery deepens. Betty Carter denies her midnight marriage to the victim. A clergyman lies about his presence at the deathbed. Thirteen letters from Canada bear a cryptic stamp code. And somewhere in the sprawling Lodge lies hidden the legendary Paltoff diamond—a Russian imperial jewel that men would kill to possess. From the elegant drawing rooms of Washington society to the snow-covered fields of Maryland, Trenholm and Miriam must untangle a conspiracy that reaches from the aftermath of the Russian Revolution to a isolated country estate. With each decoded message, they draw closer to a killer who will stop at nothing to claim the lost jewel. But time is running out, and the thirteenth letter holds the key to a suicide’s grave—and a hidden fortune.