Nat Spiller, an admired climate change activist, has accidentally drowned. That's the police verdict. But was it an accident? His partner Ellie thinks otherwise.Pam, Ellie's aunt, draws a reluctant Lauren Fraser into the mystery. The formidable Lloyd, Nat's father, head of Spiller Developments, tells Lauren to butt out and it looks as if Nat's brother Justin might follow through on Lloyd's threats. But as Lauren investigates, suspects begin multiplying. Was it Harold the bird-watcher, envious of Nat's charisma? Or Derek, whose shonky Antarctic climate science Nat was about to expose? Perhaps it was Rodger, obsessed with Ellie and wanting her for himself?Lauren enlists her circle of friends to help build the evidence for murder. The truth catches them all unawares.