David Giuntoli, Grimm

Is it a riff on the old Pied Piper story...or Glee gone bad? On a special Thursday episode (10/9c) of NBC's fairy-tale-inspired crime series Grimm, a teacher at a performing-arts school will die gruesomely, leaving many of the students on the suspect list Nick (David Giuntoli) must investigate. "It's a very ambitious episode with really cool techno music and a buttload of rats," says exec producer David Greenwalt. "It is not for the faint of heart."

That's followed tomorrow night — in the show's normal Friday-at-9/8c timeslot — by an hour of revenge featuring pigs and the wolves who've hunted them for centuries. Drop Dead Diva's Jaime Ray Newman guest stars as a hot 'n' hairy number who shares a stormy past with Monroe (Silas Weir Mitchell). "She is a real wild ass," Greenwalt notes. "And by that I don't mean donkey. On our show, you have to clarify that! Wait till you see Jaime wolfing out. It's really amazing."

Then, on December 16 comes a story of a feral teenager who hides in the woods and hasn't been to a hairdresser in years. "It's a very cool telling of the Rapunzel story," says exec producer Jim Kouf. "She doesn't just use that long braid of hers to climb up and down stuff. She uses it with violent intent."

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