Evil Under the Sun by Agatha Christie

The beautiful bronzed body of Arlena Stuart lay facedown on the beach. But strangely, there was no sun and she was not sunbathing... she had been strangled.

Ever since Arlena's arrival the air had been thick with sexual tension. Each of the guests had a motive to kill her. But Hercule Poirot suspects that this apparent 'crime of passion' conceals something much more evil.