Debutantes seeking to court a wealthy gentleman are murdered one-by-one. Meanwhile, Julia experiences post-traumatic stress from her near-death experience.
Murdoch closes in on the debutante murderer and Julia faces her demons as a great fire tears through the heart of Toronto. Contains actual footage from the fire, which is blended in with the story line.
Murdoch is reunited with Freddie Pink, his childhood friend turned private investigator, when she claims that one of her clients has been murdered. However, a missing body and evidence implicating Freddie suggests that she knows more about the case than she is saying.
New scientific evidence results in the exoneration of a man Murdoch helped put away for murder twelve years previously. Although Murdoch still believes the man to be guilty, he is removed from the new investigation. Detective Watts from Station House One takes over.
Murdoch and Ogden investigate the poisoning of a philandering businessman. Meanwhile, Rebecca James has suspicions about a fellow medical student's suicide.
As Murdoch investigates the strange death of a footballer, Brackenreid gets caught up in the team's run for the Olympics.
A serial killer begins murdering men with cyanide laced lipstick, and all the murders seem to be connected to Crabtree's girlfriend, Nina Bloom.
Key witnesses against an accused murderer are killed one by one. To catch the hitman, Murdoch makes it seem like the last witness is still alive.
A lecherous criminal known as The Lurker causes mischief in Toronto, and James Pendrick returns to town with a newly invented energy drink which may hold the key to eternal youth.
Brackenreid has left Station House Four in order to accompany James Pendrick on his quest to Panama to retrieve his potion of youth. In his absence, Murdoch is appointed acting inspector, and must deal with a murderer who claims to be possessed by the spirit of Murdoch's arch-nemesis, James Gillies.
A wealthy woman's dog is murdered shortly before a high stakes dog show. Murdoch reluctantly investigates after being ordered by the owner's brother-in-law – the mayor. Meanwhile, Detective Watts returns and begins investigating a tenuous link between several missing persons cases from the past few years.
The supposed heir to a large fortune miraculously reappears twenty years after being kidnapped and presumed dead. Murdoch attempts to determine whether the man really is who he says he is, but the case becomes increasingly complex when two bodies are found. Back at the station, Detective Watts continues his missing persons investigation.
Murdoch and Ogden bury a cadaver on their land in preparation for a forensics training exercise. When the site is excavated six months later, multiple bodies are found. Elsewhere, Detective Watts attempts to track down a mysterious woman who appears to be the key to his missing persons investigation.
Brackenreid returns from Panama with the news that James Pendrick has been murdered. Even more astonishing, however, is the fact that he appears to have been rejuvenated by Pendrick's youth potion. When Murdoch starts aggressively marketing the potion, offering eternal life to the highest bidder, Crabtree becomes dismayed by the detective's disinterest in solving Pendrick's murder and starts his own investigation.
Detective Watts' missing persons case comes to a head when one of the women he has been searching for is killed in a bombing. In the ensuing investigation, Watts and Murdoch discover the rest of the missing women have been living in a commune for abused or wronged women, where men are not allowed. Needing someone on the inside, Murdoch asks Freddie Pink to infiltrate the group.
When a badly decomposed body is found in an empty building, Murdoch's prime suspect is a death-obsessed young man named H. P. Lovecraft.
Murdoch investigates the death of an expert roller skater. Meanwhile, Miss James enters a roller race against a group of women who have slighted her, and George faces relationship issues.
Murdoch goes underground after becoming the prime suspect in the murder of a burlesque dancer who was found dead in his bed. While Station House Four protest his innocence, the newly reappointed Chief Constable Davis and the corrupt head of the City Council spearhead an aggressive manhunt for the missing detective.