Detective Chief Inspector Hannah Scarlett of the Cold Case Squad has reopened the case of Emily Friend who, seven years ago, was found drowned in just a few inches of water in the Serpent Pool. Hannah must determine whether this was suicide or murder.

Hannah's life is now complicated with doubts about her partner, Marc Amos, a secondhand book dealer. One of Marc's best customers, with a collection of rare books, is found burned to death in his boathouse. Then there is a series of deaths of other collectors in gruesome circumstances. Hannah must bring all her resources to clear Amos and find the sociopath who is obsessed by Thomas DeQuicy's tract "On Murder" before he can fulfill his destiny to make the tract come true, Hannah finds a link between the cold case and the current murders.

This is an absorbing story about the world of rare books and the drug-fueled writings of 19th century author Thomas DeQuincy, who was brilliant but opium addicted. There is no lack of jealousy and obsession, which leads to enough twists and turns to keep the reader on tenterhooks until the final solution.