Detective William Murdoch (Yannick Bisson, Sue Thomas: F.B.Eye) and his friends face new challenges in Edwardian Toronto as the award-winning Canadian mystery returns. With Murdoch languishing in jail for murder, Constable Crabtree (Jonny Harris, Still Standing), Inspector Brackenreid (Thomas Craig, Coronation Street) , and Detective Watts (Daniel Maslany, Goliath) race to prove his innocence, while Dr. Julia Ogden (Gemini® winner Hélène Joy, Durham County) remains in hiding from the corrupt forces that have taken over Station House No. 4. When the dust settles, Murdoch and his team solve cases featuring poisoned wine, high-speed transportation, botched organ transplants, and anti-Semitic riots, along the way encountering historical figures like Helen Keller, Alexander Graham Bell, and Theodore Roosevelt. Guest stars include Tamzin Outhwaite (New Tricks), Colin Mochrie (Whose Line Is It Anyway?), Peter Keleghan (Workin' Moms), David Hewlett (The Shape of Water), and WWE Raw and Smackdown! star Jay "Christian" Reso.
When the father of the groom drinks poisoned wine during his toast to the wedding couple, Murdoch and Watts investigate Toronto's community of wine lovers. Now finished with her schooling, Rebecca looks for a new job.
Murdoch and Julia attend an experiential dinner in the dark honoring Helen Keller, but when the lights come back on, one of the guests is dead. Murdoch works with Alexander Graham Bell to uncover the culprit.
At the Toronto Medical Exposition, a surgeon approaches Murdoch claiming that his organ-transplant operation was sabotaged, resulting in the death of his patient. Brackenreid's son John joins Station House No. 4.
Murdoch and Julia's dinner with Dr. Osler, Julia's mentor, is interrupted when a man accuses Osler of murder. Julia trains her new morgue assistant, Violet, while Crabtree receives a visit from journalist Louise Cherry.
An Indian diplomatic couple approach Murdoch for help finding their sons, who went missing from a prestigious boarding school. When none of the other students will talk, John and Crabtree go undercover at the school to find out what they're hiding.
While on a camping holiday, Murdoch and Julia discover a man stabbed through the heart. To catch the killer, Brackenreid picks up the paintbrush again to infiltrate an artists' group that the victim had been associated with.
When two men die after seeing their own obituaries in the newspaper, Murdoch tries to protect other people with fraudulent obituaries who are still alive. To Crabtree's disappointment, Nina considers a job in Paris.
A switchboard operator reports receiving a strange call, and hours later a man is found dead with a coded note in his pocket. Murdoch's investigation brings him to an investor's meeting for a high-speed transportation invention created by James Pendrick.
