When ambititious MP Raymond Keane is found dead in a frozen lake, Superintendent Lambert and Sergeant Hook soon discover that the politician was adept at making enemies. There is his former lover, Moira Yates, whose life he has ruined; his business partner Chris Sampson; Joe Walsh, a disgruntled constituent; and his supposed fiancée, Zoe Renwick, who had been on the point of breaking the engagement off. Moira Yates seems to have the perfect alibi. Since her break-up with Keane, she has been afflicted with agoraphobia, and is unable to set foot outside her house. In fact, all the suspects have alibis, but, one by one, they are challenged by the dogged police work of the two detectives. And when Lambert finds an object by the lake, he is sure he has his murderer...