My husband''s lover. They said her death was a tragic accident. And I believed them . . . until now.

Carmen is happily married to Tom, a successful London lawyer and divorcé with three children. She is content to absorb the stresses of being a stepmother to teenagers and the stain of ''second wife''. She knows she''ll always live in the shadow of another woman - not Tom''s first wife Laura, who is resolutely polite and determinedly respectable, but the lover that ended his first marriage: Zena. Zena who was shockingly beautiful. Zena who drowned swimming late one night.

But Carmen can overlook her husband''s dead mistress . . . until she starts to suspect that he might have been the person who killed her.

''Absolutely gripping, I raced through Undertow at the speed of knots'' Rosamund Lupton.