Nicholas Lakefield, a man sentenced to death, breaks out of prison and roams the Victorian Era London streets. William Orsburrough, Chief of Scotland Yard, has tasked Detective James Suhlyer with apprehending him. Both sides begin preparations to stay ahead of the other. In the course of the investigation, James is attacked and injured by Nicholas. He is cared for by a nurse, Heather Ashcraft, who forms an attachment to James and becomes involved in the pursuit of Nicholas. Although initially, they all believe that Nicholas is mad and running amok, they gradually discover that he was innocent. The truth is that Nicholas is seeking to expose Kirkland, the real villain, and exact revenge. Throughout the story Nicholas has been picking off Kirkland's accomplices one by one. Nicholas knows that Kirkland has been kidnapping citizens and running experiments to bring the dead back to life and create other unholy abominations. There is a confrontation with one of Kirkland's creatures later in the book. Kirkland leaves Nicholas and James for dead after a confrontation and throws them into a dungeon where this creature resides. This conflict and the discovery of Kirkland's actions cause Nicholas and James to join forces. Throughout his ordeal and before he is made to work alongside James, Nicholas feels that he has nothing to lose and is ruthless in his determination to bring Kirkland to justice. Whatever the cost and regardless of the consequences. During his mission of revenge, he meets an old friend, Arthur Burns, who tries to make him realize that he is in danger of losing his humanity. Damaged by his long years of imprisonment, Nicholas is adamant in his refusal to accept this. He is going to follow his mission through, irrespective of the moral implications. The theme of morality and what limits one will go to due to trials and tribulations is a re-occurring one throughout the novel. Whether it is okay to become a monster, to defeat a monster. If it is worth fighting fire with fire, or if the ends will truly justify the means.