Grimm is closing in on its 100th episode, and as such, the mystery of the seven keys will soon be thrust back into the spotlight. A three-episode arc is on the way, and NBC has already slipped the first piece of the puzzle into place.

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The cartographic mystery has plagued Nick (David Giuntoli) since day one, but the arrival of Monroe's (Silas Weir Mitchell) uncle in "Map of the Seven Knights" may give the monster hunter a leg up in the supernatural competition. Unfortunately, it sounds like Royals will no longer be the Grimm's No. 1 competition.

"Monroe gets a call from a relative in Germany that will bring Nick closer to his ancestors," NBC teased. "Things get complicated when the nefarious group Black Claw is also after the same artifacts."

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Felix, our beloved Blutblad's uncle, will be in possession of several Grimm-related tomes. His arrival will no doubt be a boon to Nick following Juliette's (Bitsie Tulloch) decision to torch his trailer.

"In the course of his work as an antiquarian bookseller, Felix will come across some very old volumes about Grimms...then find himself followed by those who are willing to kill in order to secure the books," TV Line teased.

Set to air as the 10 the episode of season 5, "The Map of the Seven Knights" will be followed by "Key Move" and the series' milestone episode, "Into the Schwarzwald."

Grimm airs Fridays at 9 p.m. ET on NBC. Check out a preview for the midseason premiere, "Eve of Destruction," by clicking the video below.

Tags: Grimm television nbc