Volcanalis

Opening quote: "The demon came home, and he declared that the air was not clear. 'I smell the flesh of man."

In the Mount Hood, a geologist, Jill Prembrey (Nicole Santora) retrieves rocks near a fumarole. Then, she is attacked by Markus Hemmings (Gill Gayle) who tries to get back the rocks but she manages to escape. He then woges into a Taureus-Armenta. Later, Jill is killed at her home by a creature covered in lava called Volcanalis.

In the station, Hank (Russell Hornsby) is sent on vacation on behest of Nick (David Giuntoli), Wu (Reggie Lee) and Renard (Sasha Roiz). In Vienna, Adalind (Claire Coffee) is taken by Frau Pech (Mary McDonald-Lewis) to visit Stefania Vaduva Popescu (Shohreh Aghdashloo), who explains that a bloodline must be established for the child and they subdue Adalind to perform an extraction of the fetus' blood.

Juliette's visions continue haunting her, to the point where she crashes her car. She then visits Pilar (Bertila Damas) for help and she is given a tea to help her to focus and enter again in the past in an attempt to get the memories back. Nick and Wu go to the fumarole with Jill's boss to investigate the scene, where the boss retrieves rocks from the fumarole while Markus unsuccessfully tries to stop them.

Adalind's test shows that the baby is of Royal blood and offers her money for the baby when is born. Adalind refuses the money, preferring to get her Hexenbiest powers back. Upon finding out that Markus's wife was killed years ago, Nick and Renard bring him to the station. He claims that he didn't kill the archaeologists, he was in fact warning them of the danger that would happen to them and they were killed by a creature named Volcanalis for stealing its rocks.

The boss is killed by the Volcanalis that night and Nick tries to fight him back but he is no match for him. With information from the trailer, Nick, Renard and Monroe (Silas Weir Mitchell) find that the Volcanalis is responsible for the eruption in Pompeii. They decide to call Markus for help as he is an expert on the topic. Markus claims that nothing can stop it "until hell freezes over". Nick then gets an idea to use liquid nitrogen to kill him.

Nick, Monroe, Renard and Markus go to the mountain and take the rocks to a warehouse to wait for the Volcanalis to arrive. Using Markus as a bait, the Volcanalis appears and while advancing towards him, Nick, Monroe and Renard use the liquid nitrogen hoses to wash him and freeze him as a solid rock. Seeing he is still alive, Nick gives Markus a hammer to kill it so he can avenge his wife. Markus hits the Volcanalis until its eyes freeze over. Meanwhile, Juliette decides to remake the previous memories of Nick and she manages to control the problem. The episode ends as she now remembers the memory of Nick proposing to her.