"And glory like the phoenix
midst her fires,
Exhales her odours. blazes,
Mason and Joan are taking inventory in an outdoors store, when Barstow, who is a Excandesco, woges and sets the store on fire. The store busts into flames which quickly multiply when in an attempt to get out, Mason throws a chair throw a window.
Juliet has a flashback to woging and killing the Wesen who attacked her. Juliet and Nick talk about what he did with the body and what Adalind might do once she discovers that Nick is a Grimm again.
The next morning Nick and Hank arrive at the store and the details from Wu. Nick and Hank go over the scene and shown that the fire inexplicable turned. They head outside to speak to the owner and his son John and Andy Harrison briefly. Back in the car, they question what explains a fire with a mind of its own and wonder if this is an insurance scam. Back at the station, Hank gets off the phone with the insurance and of course Harrison & Sons had a five million dollar policy on the store and had just filed for bankruptcy. Nick and Hank decide to talk to the lawyer who filed the bankruptcy and ask for a list of the debtors and the company's financial records.
At the station, Sam reports that Kelly sold the truck she left Portland in. Renard decides to check a listing of all vehicles sold, sure in the knowledge that Kelly is going to need a car.
Now back at the station, Nick asks Wu to run a background check on Charles Laney, the lawyer handling the bankruptcy for Harrison & Sons. Wu mentions that an officer in arson says that the fire pattern matches one his former partner was obsessed with. Hank and Nick want to talk to the cop but find out that Orson may not be receptive because they arrested for murder.
At the prison, Orson who is a Bauerschwein, woges when he hears that Hank and Nick want to see him, saying "hell no." While waiting for Orson, Nick explains that he didn't really know what was going on back then because he was just coming into his Grimm powers. Orson makes his way in and they tell him about the fire and he snarks about doing Nick's job. Nick shows Orson the pictures of the victims, adding that no accelerant was used and that Grady suggested Orson might know who they are looking for. Orson says that he would have caught the arsonists but then Nick arrested him, adding that if he saw him again, he could identify him.
When next we see Orson, he is in the police station with an ankle monitor on and is escorted into Renard's office. Renard explains to Orson that he has two days to assist the detectives and if Orson messes up, he will never get parole. Orson starts to become vague about the arsonist and so Nick asks if the arsonist is a Wesen and Hank reveals that he knows that Orson is a Bauerschwein and that Nick is a Grimm. Orson is shocked, then reveals that the arsonists likes to light a fire and then stick around and watch. Nick tells Hank and Orson to look through the files while he does some research.
At the Grimm trailer, Wu and Nick find out that the wesen they are looking for is a Excandesco. The story that Nick reads is the Roman fire which was on blamed on Christians. Yes, more historical appropriation from Grimm but at least because it's ancient history, it's not as horrifying as their recent acts of appropriation. Unfortunately, the Grimm wiki has no information on how to stop a Excandesco.
Charles Laney meets with Barstow and reveals that there were two kids inside the Harrison building and that two homicide cops came to see him. Barstow argues that this is not his fault but is told that he has to clean house get rid of everyone who can identify him. Barstow takes Laney at his word, grabs Laney's throat and sets him on fire.
Orson and Hank are talking, when Nick enters to ask if Orson has ever heard of an Excandesco. They wonder if the arsonist is the accelerant himself. Orson explains that the arsonists could essentially be a human match. Nick and Hank talk about how to arrest the arsonist, if they cannot get close to him. Orson suggests that he can make something to protect the Nick and Hank. Hank suggests that the spice shop might have the things they need. Nick decides that he should call first because of the history between Orson and Monroe. When Nick gets a hold of Rosalie and learns that Monroe is going to be gone for several hours, he decides to head over.