The countdown to the 100^th episode of "Grimm" starts with episode 10. And what better way to kick things off than with an episode showcasing the Wesen that has been Nick's loyal ally through thick and thin – Monroe.

A synopsis for episode 10 reveals that Monroe (Silas Weir Mitchell) will receive a call from one of his German relatives. Previous reports revealed this relative is his Uncle Felix and he has something that will bring Nick (David Giuntoli) "closer to his ancestors." Unfortunately, whatever it is he has is also something that the Black Claw wants. The upcoming episode will also see Capt. Renard (Sasha Roiz) helping his mayoral bet get an advantage over his opponent while Trubel (Jacqueline Toboni) confronts Eve (Bitsie Tulloch) about Nick and Adalind's (Claire Coffee) situation.

"Grimm" fans will certainly enjoy the trailer for episode 10 as it harkens back to the good old days when it was just Nick and his Blutbad buddy. The Monroe-centric trailer begins with two Anubis wesens attacking a woman. Nick calls Monroe, who's with his uncle and Rosalee, and asks for his help. Monroe is then seen in a stand-off with the two Anubis from earlier. He woges and tells them they "shouldn't have done that." The clip's final scene shows Monroe killing one of them.

The trailer also asks "who's afraid of the big bad wolf?" and it's obvious that Monroe, for all his quirks and lovable personality, is still a force to be reckoned with. The previous seasons have shown that he's willing to fight and die for his love ones, and maybe that's the reason he killed one of the Anubis. Photo stills from the upcoming episode show his uncle covered in blood.

Interestingly, this season's 10^th episode is also the series' 98^th episode. Showrunners Jim Kouf and Norberto Barba had promised fans that the mystery of the keys will be resolved on "Grimm's" 100^th episode and they're making good on that promise.

Episode 10, "Map of the Seven Knights," will kicks off the trilogy of the keys that will culminate in episode 12, "Into the Schwarzwald." In a Blastr interview, Barba revealed that in episode 100, "Nick and Monroe go on a big trip because of the keys, and they find where the keys are." Hopefully, the keys will give Nick an advantage in the on-going Wesen war.

Episode 10 of "Grimm" season 5 will be aired on Feb. 19.