Hold on to your hats, Grimm fans, the seven keys mystery will take the series by storm this fall.

'Grimm' Season 5 Spoilers: Nick Burkhardt Is On The Move, Where Will He Hide His Baby?

It was previously announced that the mysterious atlantean puzzle would figure into Grimm's 100th episode, but unless the NBC series is filming out of order, it appears the keys will crop up two episodes ahead of the landmark undertaking. While the producers have promised a deep look into the long running story for the untitled 12th episode, Spoiler TV recently announced that episode 10 will be called "Map of the Seven Knights."

Excited yet?

'Grimm' Season 5 Spoilers: A New Partner For Hank, 'Clear & Wessen Danger' Plot Revealed

The story of the seven keys has been floating around since day one, but for those who have forgotten the details, we've put together a little recap:

When pieced together, the keys of the seven knights will form a map that will lead the bearer to a treasure of sorts. Nick Burkhardt (David Giuntoli) holds two pieces of the puzzle, the Royals currently have four, and one key remains entirely unaccounted for. Based on the clues Nick has, he and Monroe (Silas Weir Mitchell) have determined that the map leads to a location in Germany's Black Forest.

It sounds like Nick will have more to worry about than the rise of the Wessen when midseason rolls around.

Find out more when Grimm returns to NBC on Oct. 30. Click the video below to see a preview for the season 5 premiere, "The Grimm Identity."

Tags: Grimm television nbc