You Don't Know Jack

"" is the twentieth episode of Season 4 of Grimm and the eighty-sixth episode overall. It first aired on May 1, 2015 on NBC.

Press Release
A SERIES OF CONNECTED MURDERS LEAD EVERYONE TO THINK A COPYCAT IS ON THE LOOSE - GARCELLE BEAUVAIS AND NICO EVERS-SWINDELL GUEST STAR - A string of homicides have the press asking Captain Renard (Sasha Roiz) if a Jack the Ripper copycat has arrived in Portland. While dealing with the investigation, Nick (David Giuntoli), Hank (Russell Hornsby), Monroe (Silas Weir Mitchell) and Wu (Reggie Lee) deal with a situation they never expected. Meanwhile, Adalind (Claire Coffee) and Rosalee (Bree Turner) must work together on a last ditch attempt to fix Juliette's (Bitsie Tulloch) condition. Elsewhere, Juliette decides to help her new ally even if it means hurting those around her.

Wesen

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

Production Notes

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

Continuity

 * Bud meets Adalind for the first time.
 * The first female Klaustreich is seen.
 * The trailer is badly damaged, but not all of its contents have been destroyed; subsequently, the remaining items, including some of the Grimm diaries and weapons, are moved to the spice shop basement.
 * It is revealed that Lauren Castro did not succeed in her campaign to become the mayor of Portland.