Good detectives, great partners.
Detective Charlie Hudson teams up with what he calls his "highly trained law enforcement animal" German Shepherd dog named Rex who he prefers to team up with because he doesn't talk his ear off. Based on the Austrian–Italian series, Kommissar Rex.
When the sole witness against the son of a powerful mob boss goes missing in the woods, it's up to Mark, Rex and Jesse to track him down. The mob boss has already hired an assassin to find the witness.
A young lawyer is snatched off the street, but the team can't track her down until they locate the sole witness - a child who disappeared from the scene. Rex connects with the traumatized boy, who communicates primarily through drawing. The team races to uncover who is behind the kidnapping and at the centre of a money laundering scheme before the criminal rids themselves of their depreciating asset.
When businessman Jake Kaufman is found dead on his yacht, all suspicion falls onto a deckhand who ran from the scene. As Mark and Rex search for motives and clues, it seems that the businessman's missing watch might be what the killer was after... But with Rex being unable to find traces of the watch on any of the suspects, the hunt for the elusive watch and the killer becomes a race against time to save another life.
An announcement on the future of the Devereaux Gin Distillery is cut short when the owner is found drowned in his own spirits. The three heirs to the family business become prime suspects as Rex sniffs out the secret ingredient behind a groundbreaking new gin recipe, while Mark revisits the night of the murder to put the family drama to rest.
When a survivalist competition broadcasts a finalist's body live on air, the team must figure out who was serious about burying their competition. Mark and Rex discover that the staged bear attack was actually murder, but the show must go on. Rex's keen hearing reveals a dead giveaway in the botched broadcast, leading the team to stage their own finale to catch the killer - live on TV.
When a conspiracy theory podcaster is found murdered just before her talk at the TruthCon conference, Mark, Rex and the team find themselves thrown into the extreme world of conspiracy theorists. They find that one of the theorists is Mark's old commanding officer, now afflicted with PTSD. In the end, it's Rex's relationship with the old soldier that might lead them to the real killer.
Sarah and Rex are kidnapped by an old enemy - criminal mastermind Rupert Mankiewicz. Mankiewicz's mission is to exact revenge by weaponizing Rex. Mark and Jesse launch a desperate investigation to find them before Mankiewicz can fulfill his deadly mission.
Birdwatching tourists are ruffled when they spy the body of a landowner who had hidden the nesting site of the rare Red Crossbills from them. When the team unearths a ruby from a 25-year-old jewelry heist connected to the case, Rex tracks the birdsong to find the treasure at the secret nesting site, before the killer can get there first and destroy the endangered birds standing in his way.
When a pro wrestler is murdered days before a charity event, Mark and Rex must unmask the villain to save an animal shelter.
When a master painting instructor is pushed off a cliff, Mark and Rex scope out the art world to get to the bottom of a picture-perfect murder
When firefighter trainees discover a real cadaver during a controlled fire exercise, Mark and Rex follow one burning clue after another.
After a fisherman's body is reeled in with the morning haul, every suspect seems to have an alibi, but the team senses something fishy about the autopsy.
After a robbery interrupts the team's holiday plans, Mark and Rex must track down the masked members of a Newfoundland mummering gang.
With Rex and a puppy lost in the wilderness days before Christmas, Mark races to reunite with his partner.
