As Juliette begins to fully embrace Nick's life as a Grimm, Eric Renard's undead plot threatens to bring all of Portland to a panicked halt. Meanwhile, Adalind makes a desperate push to get her powers back.
Nick and Hank rush to stop a dangerous man assembling an "undead army," as Monroe and Rosalee finally show Juliette their Grimm sides. In Vienna, Adalind tries to sell her unborn baby in exchange for her lost powers.
Mysterious cow mutilations put Nick on a case that forces him to question the existence of aliens within the Wesen world. Meanwhile, Nick digs further into the key, and Juliette's romantic memories of Nick start coming back in a big way.