The mystery writer Harriet Vane, recovering from an unhappy love affair and its aftermath, seeks solace on a barren beach — deserted but for the body of a bearded young man with his throat cut. From the moment she photographs the corpse, which soon disappears with the tide, she is puzzled by a mystery that might have been suicide, murder or a political plot. With the appearance of her dear friend Lord Peter Wimsey, she finds a reason for detective pursuit — as only the two of them can pursue it.