A rock concert awakens the legendary monster, who goes on a rampage. The event's organizer plans to kill the beast and create a tourist attraction around its stuffed body, but an environmentalist realizes the creature is the last of its species, and is determined to make sure it does not become extinct.

After Portland homicide detective Nick Burkhardt discovers he's descended from an elite line of criminal profilers known as "Grimms," he increasingly finds his responsibilities as a detective at odds with his new responsibilities as a Grimm.