Detective Murdoch investigates when a wealthy family's pregnant maid is found dead in an area frequented by prostitutes.

When Detective Murdoch's friend and protege, Constable Oliver Wicken, is found shot to death in the basement of an abandoned house, the constabulary decide it was suicide. Murdoch is determined to prove it was murder and clear Wicken's name.

Detective Murdoch investigates the murder of Dolly Capshaw, a mid-wife who, it turns out, was also an abortionist.

At a charity gala for sick children, Murdoch and Dr. Ogden find the host, dressed as Santa Claus, dead from a broken neck. To make matters worse, all the presents that were collected for the children have been stolen. When witnesses report hearing a wild animal near the scene, Inspector Brackenreid suspects the legendary creature Krampus. Meanwhile, Constable Crabtree worries he'll have nowhere to spend the holidays.

Four days before Christmas in Edwardian-era Toronto, Detective William Murdoch is called to investigate a daring train robbery. When witnesses insist the culprit exhibited superhuman abilities, Constable Crabtree realizes the robber bears a striking resemblance to the title character of his new graphic novel, Jumping Jack. As Station House No. 4 contends with a real-life Jumping Jack, Inspector Brackenreid orders the formation of a police choir, and Dr. Julia Ogden tries to help two orphans who mistake her for a fairytale heroine.