After the mysterious brutal attack of a local college co-ed, Portland homicide Detective Nick Burkhardt discovers he is descended from an elite line of criminal profilers known as "Grimms", charged with keeping balance between humanity and the mythological creatures of the world. As he tries to hide the dangers of his new found calling from his fiancée, Juliette Silverton, and his partner, Hank Griffin, he becomes ever more entrenched in the ancient rivalries and alliances of the Grimm world. With help from his reluctant confidant, Monroe, a reformed Grimm creature himself, Nick must navigate through the forces of a larger-than-life mythology.

After a case of breaking and entering has one of the intruders go missing, Nick and Hank talk to a mysterious family whose cultural background blurs the line of right and wrong. Meanwhile, Nick tasks Monroe with the safeguarding Aunt Marie, who was almost killed the night prior by a hexenbiest.

The station is abuzz as Nick and Hank are called to a case where an innocent flash mob results in a gruesome homicide. As Nick delves further into the investigation, he learns more about his unique family history, and finds himself at odds when he and Hank are assigned to protect a dark character from his recent past.

After investigating a strange cluster of female deaths and disappearances, Nick sends Monroe undercover to get a whiff of a hypnotic suspect. In the meantime, a stranger shows up looking to avenge the death of his friend at the hands of a Grimm, but he'll have to get past Captain Renard.

Nick and Hank's investigation of a dead high school teacher leads them to the school's outcast, Roddy. Nick realizes that there's more to Roddy than meets the eye, and enlists Monroe's help to get through to the troubled teenager before he exacts revenge on the students who wronged him. Meanwhile, Nick learns that his presence is beginning to affect the creature world.

Nick is called to a suspected arson case, which exposes a longstanding family feud that brings Monroe face-to-face with characters from his troubled past. While Monroe wrestles with restraining his wild side, it's up to Nick to keep everything from going up in flames.

A mysterious homicide deep in the woods leads to Nick and Hank reopening a long-cold missing persons case. When Nick suspects this abducted person might be a feral creature, he asks Monroe to help remind this wild child of her human nature.

An escapee returns to Portland seeking revenge against those who put him behind bars, including Hank, the arresting officer. His unusual strength and high tolerance for pain makes Nick suspicious that he might be more than human. As the case escalates Nick and Juliette are put in danger, and Monroe is called into action to help put an end to the convict's deadly rampage.

While investigating a gruesome homicide, Nick learns that a seemingly mild-mannered resident could be festering a potential monster created from a dark childhood. Meanwhile, Monroe is sent an unsettling message by the creature community, who are beginning to wonder if his priorities lie with them or a Grimm.

As Portland’s homeless youth start to go missing, Nick uncovers a deadly black market supplying the Grimm world with human organs for all types of elixirs. As the investigation heightens, Nick and Juliette befriend a pair of homeless siblings, Hanson and Gracie, whose friends have gone missing.

Nick and Hank find themselves on the hunt for a deadly heartbreaker leaving behind a web of dead bodies. Meanwhile, Nick’s growing recognition among the creature world is starting to threaten not only his safety but Juliette’s as well, and it may be time for him to take action to keep her safe.

A bizarre double homicide leads Nick and Hank to a boxing gym, which Nick discovers is a supplier for a darker, ritualistic fight club in the creature world. When Monroe lends a hand and gets in over his head, Nick must dig deep and find his inner “Grimm” to defend him.

A failed jewelry store robbery results in a murder that finds Nick and Hank immersed in a hunt for rare coins. Nick soon learns that these coins have an unsettling effect on whoever possesses them, as Hank and Captain Renard begin to exhibit unusual behavior. Meanwhile, a mysterious old friend of Aunt Marie’s comes to Nick with information about his family and what led to his parent’s death.

While investigating an arson-related homicide with Hank, Nick finds himself in the heated world of Portland fire-dancing where he meets a woman who might just be too hot to handle. With Monroe’s help, Nick will have to find out if he can investigate the case without getting himself or those close to him burned.

After the grisly murder of a familiar shop owner, Nick joins forces with Monroe to help solve the murder. When the shop owner’s sister, Rosalee, comes to town, Nick thinks he may have found a new ally in the creature world. Elsewhere, Captain Renard enlists Adalind to cast a spell on Hank. Meanwhile, Sgt. Wu unwittingly becomes entangled in Adalind’s dastardly plan.

Nick pulls out all the stops to plan a romantic getaway for Juliette in an attempt to get their relationship back on track. Nick’s duties as a Grimm get in the way of romance when he meets the unsettling neighbors and discovers that the troubled wife has a rare and valuable treasure to protect. It’s left to Nick to keep everyone safe. Back in Portland, Hank and Monroe each find themselves on the brink of new romantic relationships.

Nick and Juliette join Hank for dinner, where Nick discovers Hank’s mystery date is none other than Adalind, the same Hexenbiest who tried to kill Aunt Marie. Meanwhile, Captain Renard takes matters into his own hands when a visit from foreign representatives of his royal bloodline threatens his position. Elsewhere, Monroe and Rosalee are called into action when the lives of Hank and Sgt. Wu hang in the balance.

While investigating a string of murders, Nick and Hank learn that their suspect’s crime wave began overseas. When Nick discovers the suspect is being harbored by none other than Monroe and Rosalee, he realizes he’s hunting the hunted, a freedom fighter trying desperately to escape the clutches of a creature bounty hunter.

As Nick delves into the trailer’s weapons cabinet and his inner Grimm, the investigation of a dead construction worker leads him into a long standing conflict in the creature world. Sensing an unfamiliar threat, the suspect takes it upon himself to summon reapers to town to eliminate the Grimm once and for all. Meanwhile, Juliette insists that Nick invite Monroe over for dinner, making for quite the interesting evening.

Nick and Hank are called to investigate the mysterious death of a wealthy matriarch, after her stepdaughter loses everything in a Ponzi scheme. Meanwhile, Juliette does some digging into the mysterious death of Nick’s parents in an effort to help him find closure.

After Juliette stumbles upon a brutal murder, Nick learns the suspected creature, and friend of Monroe, is suffering from a mysterious condition — the inability to completely return to human form. This mysterious condition leads them to a therapist who’s created an artificial drug to suppress the creature side, with horrifying side effects. Meanwhile, the investigation takes a surprising turn when Hank sees something he can’t quite explain.

As Nick delves deeper into his life as a Grimm, a trail of grotesque murders reignites the search for the elusive gold coins. The arrival of a mysterious woman in black begins to get in the way of Nick and Hank’s investigation as extra precautions have to be taken to ensure their safety. Meanwhile, Nick’s ability to keep his true nature secret from Juliette comes to a tipping point.