Kirstin Rutherford's return to Edinburgh after two years away is tinged with sadness because five months ago her beloved father-in-law, Jamie, drowned in a deep pool in the Water of Leith, known locally as The Cauldron. And no one is sure whether it was a tragic accident, or a suicide, or something much more sinister...One person who may know is the enigmatic Morag Ramsay. For Morag's boyfriend and his lover were murdered at The Cauldron only a few months before Jamie's drowning. Morag was accused of the killings but recently released due to lack of evidence. Convinced Morag holds the key to Jamie's death, Kirstin befriends her. Yet it soon becomes clear that the brittle and unpredictable Morag is a less than reliable witness. And Kirstin's journey is making her suspicious of everyone's motives, including those who died. Who can she trust? And, more importantly, who should she fear?