After the mysterious brutal attack of a local college co-ed, Portland homicide Detective Nick Burkhardt discovered he is descendant of 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 fiancee, 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.

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.