An expedition off the Italian coast reclaims a World War II-era German midget submarine. When the two-man sub is opened, it contains a single corpse, and an artifact from Adolf Hitler's bunker that was thought to be lost to history. On Long Island, an elderly man and woman are brutally murdered. FBI Agent Link Johnsten is called in to assist local authorities and to maintain the victims' secret. When six unsent letters are discovered in their home,...