An undelivered letter with a cryptic message holds the key to an unsolved murder...

When Henry Moreland is found dead on a lonely New York road after a violent storm, it seems he died of natural causes while walking to the home of his betrothed, Eleanor Argyll. An examination of the corpse reveals, however, that he was killed by a single, powerful stab wound. His wallet was untouched, eliminating robbery as the motive-but who would want to murder the well-liked and respected man?

Richard Redfield, an old family friend who harbors a secret love for Eleanor, vows to bring Henry's killer to justice. Richard soon finds himself out of his element. Together with a legendary detective named Mr. Burton, he embarks on an unsuccessful mission to find the murderer. When suspicion turns to Richard himself, he leaves the family behind and goes to work in the 'Dead Letter' office in Washington. Then a mysterious letter from the past turns up, and a new hunt begins...