Headache

"" is the twenty-first episode of Season 4 of Grimm and the eighty-seventh episode overall. It first aired on May 8, 2015 on NBC.

Press Release
THE MANHUNT CONTINUES FOR A VICIOUS SERIAL KILLER - JACQUELINE TOBONI RETURNS AS 'TRUBEL' - While investigating a grisly murder, Nick (David Giuntoli) and Hank (Russell Hornsby) get closer to uncovering the identity of the serial killer while Wu's (Reggie Lee) life is put in grave danger. Having turned down Monroe (Silas Weir Mitchell) and Rosalee's (Bree Turner) offer, Juliette (Bitsie Tulloch) solidifies a new alliance as she works to get her revenge. Elsewhere, Trubel (guest star Jacqueline Toboni) makes a surprising return to Portland. Sasha Roiz and Claire Coffee also star. Nico Evers-Swinderll guest stars.

Wesen

 * Blutbad
 * Fuchsbau
 * Half-Zauberbiest
 * Hexenbiest
 * Eisbiber
 * Hundjäger

Non-Wesen Beings

 * Jack the Ripper

Production Notes

 * Footage from, , , , , , , , , and is reused (flashbacks).

Continuity

 * The episode picks up right after ended.
 * Renard is healed of his side effects from his mother saving his life.
 * Trubel appears for the first time since.
 * Kelly Burkhardt appears for the first time since and Diana appears for the first time since Adalind's hallucination in.
 * Diana is revealed to have aged faster than a normal person as she is now a young kid instead of a baby.
 * It is revealed that Renard, possessed by Jack the Ripper, is the one who murdered Heidi McDunnah, Mary Ann Casey, and Henrietta in.

Trivia

 * Wu's patrol car number is 421, the same as the episode number.
 * The liquid that Sasha Roiz (Renard) drank during the Dead Faint Potion scene was actually green dyed rice milk.