Spring, 1921. Scotland Yard sends Inspector Ian Rutledge to the sea-battered village of Walmer on the coast of Essex, where amongst the salt flats and a military airfield lies Benton Abbey, a grand manor with a storied past. The lady of the house may prove his most bewildering witness yet. She claims she saw a violent murder, but there is no body, no blood. She also insists she recognised the killer: Captain Nelson. Only it could not have been Nelson because he died during the war. Everyone in the village believes that Lady Benton's losses have turned her mind - she is, after all, a grieving widow and mother, but the woman Rutledge interviews is rational and self-possessed. And then there is Captain Nelson: what really happened to him in the war? The more Rutledge delves into this baffling case, the more suspicious tragedies he uncovers.