When a mangled car is pulled from the river, containing bloodstains and a gun, the sense of safety is shattered in Tessa's Californian hometown. Tessa, who works at the river conservancy, thinks she saw a girl out on the riverbank - but Tessa's memory is failing and could this be the start of something more serious? Tessa's friend and co-worker, Claire Barrett, is worried - about the car and the gun, but also about Tessa. With Tessa's attorney husband preoccupied with a big case and in denial about his wife's memory issues, Claire knows that it'll be up to her to work out what's going on. When a body turns up and she discovers the identity of the gun's owner - someone disturbingly close to home - Claire is determined to uncover the truth . . . whatever it takes.