The excitement is building among "Grimm" fans as the mystery of the keys will finally be unveiled. Is the treasure something that will help Nick as a Grimm? Or is it something that will help stop the Wesen uprising?

The previous episode saw Nick (David Giuntoli) and Monroe (Silas Weir Mitchell) traveling to Germany to try and look for the treasure that the Knights Templar hid. While they initially thought they hit a dead end in the forest, Monroe's keen eyes noticed the way several stones were arranged. While the two were busy digging, a group of Wesen arrived, apparently set on stopping them. But just as Monroe heard someone approaching, the two friends fell down a hole.

A synopsis for the upcoming 100^th episode teases of exciting and dangerous things ahead for Nick, Monroe and the rest of their group. According to Carter Matt, Nick and Monroe unearth a treasure that had been hidden for centuries in Germany. While back home in Portland, Capt. Renard (Sasha Roiz), Hank (Russell Hornsby) and Sgt. Wu (Reggie Lee) continue their search for Andrew Dixon's assassin. Unbeknownst to them, Eve (Bitsie Tulloch) is also hunting down this Wesen hitman for Hadrian's Wall. Meanwhile, someone from Rosalee's (Bree Turner) dark past returns.

The trailer for episode 12, "Into the Schwarzwald," is certain to get viewers as excited as Monroe seems to be. The clip picks up from where the previous episode ended, with Nick and Monroe deep beneath the forest floor. As they explore where they fell, Nick realizes the area must have been an old church. The two unearth a box and in typical Monroe fashion, he excitedly starts babbling about how they finally discovered the treasure that "others have searched throughout the centuries." A montage of scenes showing Nick being given a key by Aunt Marie, Kelly Burkhardt explaining the history of the keys and Adalind (Claire Coffee) and Renard trying to get the key roll during Monroe's impassioned monologue.

Aside from that, viewers can also catch glimpses of Hank kicking down the door, Rosalee being attacked by another Wesen in the spice shop, Eve in the hospital woging as she looks over a patient, Renard fighting off an attacker and Adalind looking scared while a man's fingers are mysteriously snapped. The clip ends with Nick turning one key.

The keys' story arc seems to have breathed new life in "Grimm's" ratings. According to The Futon Critic, the episodes involving the keys have seen the show's ratings go up. Hopefully, the show will be able to maintain this momentum clear through a sixth season.

The momentous 100^th episode of "Grimm" season 5 will be aired on March 11.