A young geologist is gruesomely burned after collecting rock samples from a nearby volcano, and it finds Nick and the rest trying to stop a demonic Beast who is literally hot to the touch.

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.

Nick is back on lovers' terms with Juliette, who remains eager to learn about ferals. Nick must however give priority to the violent crime wave caused by zombies. As he feared, they are created by the voodoo 'baron', who sets a trap as instructed. Captain Sean Renard informs Nick about his mistrusting meeting with visiting European royal half-brother Eric and the counterfeit documents Eric had prepared at the castle. Still in Vienna, Adalind, poisoned by Pech to switch appearances, is seen roughly overtaken by the gypsy witch's family Popescu. Rosalee prepares a zombie antidote, but once tracked down in the port, the superior zombie numbers corner down Nick's party.

Nick's destiny is uncertain as zombies continue to overrun Portland.

Monroe (Silas Weir Mitchell), Hank (Russell Hornsby), Rosalee (Bree Turner) and Juliette (Bitsie Tulloch) track down a manic Nick (David Giuntoli) and do all they can to find him and reverse what's been done to him before he causes any more damage. Meanwhile, Captain Renard (Sasha Roiz) does his best to clean up the zombie fallout on all fronts - domestic and international. Elsewhere, the more time Adalind (Claire Coffee) spends with Stefania (guest star Shohreh Aghdashloo), the more disturbing things seem to get in her quest to regain her Hexenbiest abilities.

Nick (David Giuntoli) and Hank (Russell Hornsby) investigate a cop killer who scalps his victims. Meanwhile, Juliette (Bitsie Tulloch) begins to communicate with Nick's mom via email and Adalind (Claire Coffee) finds herself much closer to delivering her baby than she previously thought. Elsewhere, Monroe's (Silas Weir Mitchell) parents (guest stars Dee Wallace and Chris Mulkey) decide to surprise him and Rosalee (Bree Turner) with an early arrival to Portland after learning some exciting news.

Monroe (Silas Weir Mitchell) fights an impossible battle to convince his parents (guest stars Dee Wallace and Chris Mulkey) to embrace the life choices he's made. Meanwhile, Nick (David Giuntoli) turns to Juliette (Bitsie Tulloch) to help him figure out the Wesen aspect of his cop-killing scalper investigation. On the Royal Baby front, Captain Renard (Sasha Roiz) learns new information that forces him to contact Adalind (Claire Coffee) in the interest of keeping her and the baby safe from Viktor (guest star Alexis Denisof).