A wealthy mobster entices three young men to work for his daughter's hand in marriage, and a surprise visitor shakes things up as Nick and Adalind struggle to adjust to home life.

Nick and Hank are called to the scene when three Wesen go out on a hunt at a local dump and get more than they bargained for when two turn up dead after they encounter the mythical Rat King. Meanwhile, a very badly wounded Trubel is taken to the hospital and Nick finally meets Meisner.

Monroe gets a call from a relative in Germany that will bring Nick closer to his ancestors. Things get complicated when the nefarious group Black Claw is also after the same artifacts. Elsewhere, Capt. Renard helps a mayoral candidate get an edge on his opponent. Meanwhile, Trubel confronts Eve about Nick and Adalind.

Newly gained artifacts take Nick and Monroe closer to the source of a long-gestating mystery. Elsewhere, Black Claw makes a deadly move that will send Portland into disarray.

Nick and Monroe find a treasure in Germany that has been hidden for centuries. Back in Portland, Capt. Renard joins Hank and Wu to track down a deadly assassin who has thrown Portland into havoc. Little do they know that Eve is on a hunt of her own for the same man. Meanwhile, someone from Rosalee's past tracks her down.