Have His Carcase

Description for HAVE HIS CARCASE by Dorothy L Sayers:

HAVE HIS CARCASE if you would; Harriet Vanes wouldn't. Being a detective writer, she did not care to become involved with the body on the" beach, even though she was escaping an unhappy love affair. But from the moment she photographed the corpse, which soon disappeared; with the tide, she was puzzled by a mystery' which might have been suicide, murder, or a political plot. With the appearance of her dear friend, the incredible LORD PETER WIMSEY, she found a reason for detective pursuit--as only the two could pursue it.

This is #9 in A Lord Peter Wimsey Mystery with Harriet Vane.