The body of an unidentified woman is found washed up on the shores of Lonesome Cove, lashed to a bit of wooden grating, with an old iron manacle on one wrist. Professor Chester Kent notices that the woman does not appear to have met her death by drowning, the town officials attempt to cover up details, and the sheriff seems to be hiding something. Meanwhile, an affluent nearby family was acting strangely after the death of the eccentric son. Kent and his friend Sedgwick try to solve the case and keep a step ahead of the authorities.