1999. A young Detective Constable Louise Mangan crosses the Thames one misty morning in pursuit of a killer. She finds a tranquil community on a leafy island close to Hampton Court Palace, but soon realises that all is not as it seems. There is something evil at play in this quiet suburb, and this junior detective’s questions seem only to scratch the surface. Twenty years later, a horrific fire brings Detective Chief Superintendent Mangan back to that same island. Soon, she discovers that murder was just a drop in these dark waters. The river runs deep, and the tide is rising at last. Will the truth rise with it?