After two young people are killed in the same way - placed in water and surrounded by flowers - DCI Vera Stanhope knows that she must catch the murderer before they strike again. Aided by her team, especially her trusted right-hand man Sgt Joe Ashworth, she unpicks the complex and dysfunctional relationships amongst a group of bird-watching friends. As the friends' loyalty turns to betrayal, Vera finds that a small act of teenage blackmail and an illicit affair may have driven someone to kill.