Nick (David Giuntoli) and Monroe (Silas Weir Mitchell) will follow the trail of the Seven Keys to the Schwarzwald/The Black Forest in the upcoming episode of the NBC series "Grimm."

In "Key Move," TV Guide reports that the "long-gestating mystery" about the ancient treasure is close to being unveiled, as Nick and Monroe come closer to the source of everything. The clues they got from the old books that Felix (Rick Overton) sent them pointed to Germany, specifically The Black Forest. After discovering three more keys cleverly hidden in the secret compartment of the trunk, Nick now has five keys on his hands. This allowed his team to create a map of the Seven Knights, the ancestors of the Grimm, from the pieces.

Nick was also able to secure detailed information about Wesens and the Grimm family tree, which included him. All the pieces are finally close to falling in the right places and he is excited with the turn of the events. Unfortunately, his friends who are left guarding the city from the Wesen attacks will have a hard time while he is away. The Black Claw will reportedly take advantage of Nick's absence to launch an all-out attack in Portland. Will Adalind (Claire Coffee) and the others be able to manage?

Meanwhile, executive producers Jim Kouf and Norberto Barba shared some details about the series' 100th episode titled "Into the Schwarzwald." In an interview with Blastr, Kouf revealed that the episode would be dealing with the keys. Up until now, the objects that are meant to be opened using the keys remain a mystery. As per Barba's description, the episode will be a continuation of Nick and Monroe's trip to Germany.

"Nick and Monroe go on a big trip because of the keys, and they find where the keys are. We see what the keys fit and we find out what's in that, and it's mindblowing. It will change things," he said.

"Grimm" season 5 episode 11 will air on Friday, March 4, at 9 p.m. EST on NBC.