During a hiking holiday to Wilvercombe after her acquittal on murder charges, Harriet Vane discovers the body of a man, with his throat cut and the blood still liquid, on an isolated rock on the shore. There are no footprints in the sand other than the man's and Harriet's. She takes photos and preserves some evidence, but the corpse is washed away before she can fetch help. Alerted by a reporter friend about Harriet's discovery of the body, Lord Peter arrives shortly after to offer his help, and he and Harriet make investigations alongside the police.
