Nick faces his toughest challenge yet when he and Hank investigate a case that combines religious phenomenon with the dark dealings of the Wesen Council. Meanwhile, Rosalee is torn when Nick's case challenges her Wesen loyalties. Elsewhere, Captain Renard leaves town to tend to some "family matters."

A traveler manages to bring a blood‑sucking legend with him as he shows up in Portland. Nick and Hank investigate the gruesome trail of “El Chupacabra.”

Rosalee disappears after some orphans decide she is the mother figure they always wanted and an encounter with a former colleague prompts Adalind to consider going back to work.

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.

Following the massacre in Nick’s loft, Capt. Renard is hell bent on eliminating him once and for all. Hank and Wu head back to the precinct to keep an eye on the Captain and help give the gang the upper hand. Meanwhile, Monroe and Rosalee grapple with staying in Portland now that their family will be expanding. Elsewhere, Eve suffers the side effects of the mysterious stick’s healing power.

Rosalee surprises Monroe with a getaway for his birthday and invites most of the gang to join them. Things take a shocking turn when a hotel employee targets Nick in an effort to avenge his father. Meanwhile, Eve gets a visit from a dark force that she has seen before. Elsewhere, Capt. Renard spends the weekend with Diana when a former ally decides to get even.

The prophecy that was uncovered comes to pass when a dark force arrives in Portland with its eyes set on Diana. In an effort to protect her, Nick, along with Capt. Renard and Adalind, returns to the scene of his first investigation as a Grimm. Back at the Spice Shop, Monroe, Eve and Rosalee make a discovery that uncovers the origins of the mysterious stick. Meanwhile, Hank and Wu are called to a crime scene that is connected to the gang's greatest threat.