Detective Charlie Hudson is a Major Crimes detective of the fictional St. John’s Police Department (in reality law enforcement in the city is provided by the Royal Newfoundland Constabulary). He is partnered with Rex, a multi-scent trained German Shepherd with an excellent ear for unique sounds. Hudson grew up reading mystery novels and as a result always wanted to be a police detective. He is partnered with Rex after Rex's K9 human partner died and Rex was scheduled to be euthanized. Rex's keen nose and ears are instrumental in helping Detective Hudson advance the investigations in each episode. The duo receive assistance from Superintendent Donovan, Forensics Chief Truong, and IT Specialist Mills every episode in gathering and interpreting evidence. The first season begins some time after Hudson has arrived back in St. John's, his hometown, following a divorce from his wife. The first case for the series is a kidnapping. Most of the season's cases different murders, each with unique twists. The episode Trial and Error varies; it is a hostage-taking situation.