Jeweler Sam Bertram was murdered by three European killers, of rival feral species, to steal the rarest Ancient gold coins from his safe. Two are dead, the third steals a uniform from a cop he murders. The coins are found on the elusive Farley Kolt, who is arrested and tells Nick enough to work out he was late aunt Marie's true love. The coins, minted on Zakynthos, with swastika's and lions heads, are poisonous and magically attract great power and utter disaster. Captain Sean Renard keeps them and starts an ambitious 'campaign against crime' amidst dreams of absolute power in Nazi style.

Nick investigates the robbery of a spice shop, that is owned by wesen, discovering that the thieves were after a dangerous drug.

Nick is in the trailer trying to find out what the key that he received from his aunt might open. Juliette calls him telling that Hank has invited them to have dinner together with Adalind. Captain Renard is forced by a criminal with a weapon to go with him to meet his cousin, but he reacts and kills them both. When Nick meets Adalind, he recalls that she wanted to kill his aunt and he confronts her near the restrooms. But he is called to investigate the murder of the two men and leaves the restaurant. Meanwhile Renard goes to the house of Catherine and she tells him that her daughter will get the Grimm's key for him. Nick meets with Monroe and Rosalee and Rosalee discovers what Adalind gave to Hank. Will she be capable to prepare an antidote and save his life?

After a man and his wife are scammed out their fortune by a Madoff-like fraudster, the husband approaches his wife's evil stepmother for financial assistance. But she refuses and is soon after murdered by a Murcielago - a bat-like creature that kills with a sonic scream.

As Nick and his mother continue to battle the Mauvais Dentes, Monroe and Rosalee fight against the clock to save Juliette. More details are revealed about the source of Juliette's illness, resulting in an epic showdown. Back at the precinct, Hank senses that something is amiss when Nick lands in hot water with the FBI. Meanwhile, Captain Renard continues to reveal himself as he deals with his estranged brother.

Monroe explains to Nick about the feral Coyotl prison gang-like, even tattooed kind's pack code when they find on old friend of Hank is actually one who fled his pack years ago and now finds his daughter kidnapped. The trail leads to their Texas relatives, the Walkers, who stop at nothing but ignore the other side has a Grimm. Nick shows angelic patience when Juliette's memory returns about everything except their love.