During a flash-mob on a bus, a lawyer is killed with a stunning overdose of bee venom, but it fits no geographical origin. Monroe and the Grim records help Nick work out it must be the work of a feral bee queen, the sworn enemy of Hexenbiests like Adalind. Trailing a professor-beekeeper and the other twelve attendants of a bee-keeping convention, Nick and his partner Hank find them congregating and get attacked by an unnatural bee swarm.

Nick learns that a series of disappearances, rapes-and possibly murders-of beautiful women in the Portland area is connected to a honeymoon hotel where the owner harbors a hypnotic power.

Nick investigates the death of a music teacher who was eaten alive by rats whille locked in his own car. Nick and Hank are led to a expelled music prodigy who has a strange sort for vengeance against those who wronged him.

While investigating the death of a homeless teen, Nick and Hank uncover a ring of Geiers harvesting human organs. Also, the Verrat threaten Captain Renard to keep the Grimm under control.

Nick and the police department goes on the hunt for a mysterious wesen woman who first seduces men and then gruesomely murders them in a "Arachnid"-related death.

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.

Park ranger Ryan Gilko is the first of several Wesen, affected by a contagious disease, who suddenly commit violent attacks on people. The team felt relaxed now Hank is being included in the secret, so Monroe takes Rosalee on a picnic. Alas, the plague spreads and even affects her, so it's up to Monroe to make the remedy they researched together while Nick holds her feral state in check. Captain Renard meanwhile learns that another terrifying European fugitive has arrived in Portland.

Those grieving for a deceased loved one becomes the target of a revolting fly-like Wesen who feeds on tears and leaves behind a deadly parasite.

Ranchhand John is killed while accidentally bumping at night into Vincent, a blue-fluorescent feral performing one of the 27 raids on cows that went from Nebraska to Portland, actually harvesting bovine ovaries for his pregnant mate Jocelyn, with whom he keeps moving and hiding. Besides Nick, the case seems to be followed only by an 'ufologist' or alien-hunter, who in fact chases the very feral species. Monroe recognizes the print Nick made from his key as part of a medieval map as Swabia, Renard explains the keys combine into a map to a terrible treasure hidden by seven crusader Grimms. Juliette swears Monroe to secrecy, being insecure about her reemerging love memories.

A mysterious drug related force begins to turn residents of Portland into feral zombies, meanwhile, Juliette learns more of the wesen community in the spice shop.

An old urban legend from within Portland sewers comes to light when a murder is committed by an vicious, alligator-like wesen.