Nick (David Giuntoli) and Monroe (Silas Weir Mitchell) will find things going against them as Black Claw launches a major attack on Portland in their absence in the upcoming episode titled "Key Move" of "Grimm" Season 5.
The synopsis of the episode reads: "With Nick and Monroe off to the Black Forest, Black Claw launches a major attack on Portland."
In the previous episode, titled "Map of the Seven Knights," the owner of "Antiquarische Buecher," Felix Dietrich, who is also an antique book dealer, got a call from a person named Andrea Stroh who told Dietrich she was calling from Prague in the Czech Republic.
Stroh told Dietrich she needed him for some books that belonged to the estate of a deceased man named Joseph Nebojsa. Dietrich immediately found the books were written by the Grimms. Afterwards, he called Monroe, his nephew, and asked whether Nick was interested in those books.
In the meantime, two Anubis Wesen belonging to the Black Claw clan murdered Andrea, and Dietrich escaped to Portland with the Grimm books. Once there, he showed the books to Nick. Though Nick didn't have any money left to buy the books, he wanted them desperately, since they would lead him to Marie's treasure Juliette burned down in the last season.
Eventually, the Anubis Wesen tracked Dietrich and killed him. Nick found out that before dying, Dietrich had shipped the books to Portland. Afterwards, both Nick and Monroe went to the shipping company from where the books were sent, and encountered the Anubis.
They had a fierce battle with Wesens, and in a fit of rage over the brutal killing of his uncle, Monroe bit the Wesens. Once the Wesens were defeated, Nick and Monroe searched for the books and after finding them, went back to the spice shop.
They found that besides a detailed catalogue of Wesen history, the book also consisted of the Grimm family tree. Monroe also found three keys, and when they combined them with the two they had, they finished the puzzle pieces of the Map of Seven Knights.