Dr Megan Banesto has returned to her childhood home of Llancloudy, a former mining village buried deep in the Welsh valleys. In her role as the village's GP, she knows the lives of her patients inside out.

But when the body of Bianca Rhys, a paranoid schizophrenic, is dragged from a murky pool, Megan questions how well she really knew her patient. In her experience Bianca has always been afraid of water - so why had she ever gone near the pool? And how had she drowned? Even though most of the villagers are unsurprised by the death and write it off as an accident, Megan is not so sure.

Megan's preoccupation with Bianca's death is further complicated by the fact that the investigating officer is an old boyfriend, now happily married, while Megan's own marriage has publicly and humiliatingly collapsed. Worse - PC Alun Williams interprets Megan's continuing interest in the case as no more than a ruse to keep contact between them.

As she discovers more about Bianca's life and death, Megan finds herself increasingly intrigued by some of the bizarre claims that Bianca used to make. What if there was a grain of truth in what she said? What if she was the only one who knew what was really going on in Llancloudy ...?