A flaming Wesen lights a store on fire, killing two young employees who shouldn't have been there so late.
Nick and Hank, investigating, immediately suspect arson due to the strange behavior of the fire. One of the arson investigators points them to his old partner, who was obsessed with catching an arsonist with a similar pattern. The only problem is that the partner is Peter Orson, a Bauerschwein Nick arrested for killing two Blutbaden in Grimm Season 1 Episode 6.
Orson offers to help them in their investigation, so they take him out of jail temporarily.
Nick soon discovers that the arsonist is an Excandesco, a Wesen that emits flammable white phosphorus from his skin. Orson has an idea on how to counteract the Excandesco's ability, but they need supplies from the spice shop.
Monroe is infuriated when he sees Orson out of jail, because one of the Blutbaden Orson killed was a good friend of his, but Rosalee reminds him that this wasn't about the Blutbad-Bauerschwein feud but the deaths of two kids in a fire.
The Excandesco begins cleaning house, killing the store-owner's lawyer, who was in on the arson. He tries to lure the store-owner's son, who hired him, but is unsuccessful. Instead, he tricks the store-owner himself into coming back to the store, where he is taken hostage.
Nick, Hank, Monroe, Rosalee, and Orson arrive at the store. While Orson distracts the Excandesco, the others locate and free the hostage. When the Excandesco attempts to escape, they spray him with the ointment they whipped up in the spice shop. The Excandesco burns up from the inside and explodes.
Orson is returned to jail, feeling better about having been a cop again for a short time.
Adalind shows up at Juliette's house and attacks her, but she is absolutely shocked when Juliette reveals her new Hexen side and they get into a knock-down fight. Adalind flees.
Nick comes home and Juliette reveals that she is now a Hexenbiest.