September 1799.

William Pitt is attempting to force through anti-slavery legislation, but many have a vested interest in preventing this change and would go to dangerous lengths to stop it.

Meanwhile, Tom Pascoe of the river police is grieving for the woman he loved and looking for solace at the bottom of a bottle. Tom's drinking has made him increasingly belligerent and unpredictable, so when he is called to investigate a body found in the Thames - that of an MP and a close associate of William Pitt - there's doubt whether he's up to the task.

But Tom must pull himself together, or be dragged under; Pitt's life is in his hands.