In St. Sebastian's Church in London, the body of a very young girl is discovered. Leaving a suicide note at home, she threw herself down from a high gallery. This case would have been considered a suicide if a drug had not been found in her blood, one that causes euphoria and suppresses the will. Inspector Mark Tartaglia and his partner, Sergeant Sam Donovan, discover that over the past two years there have been at least three more similar tragedies. A serial killer who, in correspondence with future victims, calls himself Tom, defies justice, continuing to push people toward the final line with impunity…