A failed jewelry store robbery results in a hug 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.
Detective Nick Burkhardt thought he was ready for the grim reality of working homicide in Portland, Oregon. That is, until he started to see things... things he couldn't quite explain. Like a gorgeous woman suddenly transforming into a hideous hag, or an average Joe turning into a vicious troll. Then, after a panicked visit from his only living relative, Nick discovers the truth about his visions: he's not like everyone else, he's a descendant of an elite group of hunters known as "Grimms" who are charged with stopping the proliferation of supernatural creatures in the world.
So begins his new life journey - albeit a reluctant one at first - as he solves crimes with his partner who knows something about Nick has radically changed but can't quite put his finger on it. Along the way, Nick finds himself unexpectedly getting help on some of the more difficult cases from Monroe, a guy who seems normal at first but is soon revealed to be what you might call a "big bad wolf". Literally!
Remember the fairy tales your parents used to tell you before bedtime? Well, those weren't stories, they were warnings.