It's the moment Grimm fans have been waiting for since day one; it's time to find a treasure so powerful its been hidden for centuries.

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The knights of the Seven Houses returned from the Fourth Crusade with a secret. Constantinople had furnished the conquerors with a plunder of unimaginable consequences, and the knights went to great lengths to make sure that their dangerous find would stay hidden. And they were successful, until Nick and Monroe entered the scene.

What ever the Grimm and the blutbad uncover in "Into the Schwarzwald," you can bet it will send massive shock waves through the series.

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"What they discover at the end of the 100th episode opens up a lot of new doors and introduces more questions and possibilities so it actually allows us to explore a whole other universe of ideas," executive producer David Greenwalt told Yahoo! TV. "There is lots of chaos coming. Nobody is safe."

So what is this game-changing treasure? Greenwalt thinks fans should be able to suss out the answer with a little help from their history classes.

"The answer is in real history," the EP explained. "If you know a little bit about the Crusades and Constantinople and what was there, then you could probably figure it out."

Do you know the answer? See if you're right when Grimm airs its 100th episode this Friday at 9 p.m. ET on NBC.

Tags: Grimm television nbc