The Coventry Fire was an event that occurred during the Christmas Eve incident, where a fire broke out near Coventry as a result of an assassination attempt on the Penguin's Criminal Empire arms dealer Alex Cane.
Arkham Origins Incident
At some point during the events of the Christmas Eve incident, the Penguin sent one of his arms dealers, Alex Cane, to Coventry for what was presumably an arms deal meet and also had one of his top assassins, Qing Lu, dispatched with him to ensure the success of the deal. Unfortunately, Qing Lu, an inherently ambitious man, wanted to advance up the ranks, so he decided to murder Alex Cane for an easy attempt at advancement by shooting him in the heart at close range. However, Alex Cane, despite being shot, anticipated a betrayal at Qing Lu's hands, and proceeded to throw an incendiary grenade in return, forcing Qing Lu to escape by jumping up a ledge and then climbing up a ladder, also leaving a bit of his DNA behind. The GCPD, presumably alongside the Gotham Fire Department, was then dispatched to put out the fire. However, just as they were nearly done putting out the fire, they uncovered Alex Cane's charred remains, and requested that GCPD send a forensics team to investigate.
Batman managed to learn about the fire and discovery of the body from overhearing a conversation between some cops and a GCPD dispatcher about setting up the crime scene and needing a detective to investigate shortly after he had solved a case file relating to a shooting at Dixon Docks and apprehended the man responsible. Batman, upon arrival, realized that because the fire damage made evidence collection difficult, he needed to identify the victim first. He then ID'ed the victim via dental records as Alex Cane, with his initially guessing the fire was started to cover the killer's tracks. He then realized that whoever killed Cane must have been someone Cane knew due to the close range method of his gunshot, and wondered if he had entered a deal that went bad. However, upon analyzing the fire residue near the origin of the fire, he realized that the fire had not actually been started by Alex Cane's killer, but by Alex Cane himself, and that he probably started it in an attempt to ensure his killer went down with him, though the lack of a second body suggested that his killer found a means to escape. He then deduced the killer ascended a nearby wall to avoid being overcome by the fire. He then found a footprint on the wall above the ledge, but realized it still didn't paint a complete picture as the killer couldn't have climbed the wall in the manner he did. Upon reviewing the evidence he had compiled so far and discovered a discarded ladder on the ground. Upon scanning it, he then discovered fingerprints that belonged to Qing Lu, pointing to him as the killer, and, knowing Qing Lu's ties to the Penguin as well as his trade as a top hitman, deduced his location as being at the Final Offer near Amusement Mile, although he believed Qing Lu had been hired by Penguin to assassinate Alex Cane and wondered what Cane did to deserve being assassinated.
He then tracked Qing Lu down to the Final Offer just as the latter was revealing to some of Penguin's thugs that he had killed Alex Cane due to him becoming lazy and wanting to lead an operation and recruit people. Batman then interrupted the meeting and subdued all the criminals, saving Qing Lu for last. He then interrogated Qing Lu about whether Penguin ordered for Alex Cane to be assassinated, with Qing Lu admitting Penguin not only didn't have any role in Cane's death, but that if anything, had Penguin found out, he would have Qing Lu executed for it, and revealed his motives for doing so. Batman then tells him that he won't be moving up anywhere in the world now before knocking him out cold. He then contacted Alfred telling him to supply the GCPD the location of Alex Cane's killer, alongside the evidence.
Batman: The fire damage is going to make evidence collection difficult. I should start by identifying the victim.
Scan of victim
Batman: Dental records indicate his name is Alex Cane. He's a small-time arms dealer that frequently works with the Penguin. Cause of death is a gunshot wound to the heart. The fire must have been set in an attempt to cover the killer's tracks.
Scan of impact zone
Batman: DNA evidence suggests that the killer fired from close range. This suggests the two men knew each other. Maybe it was a deal that went bad.
Scan of fire origin
Batman: Interesting. The fire was actually started by the victim. Chemical residue points to an incendiary grenade. Guess an arms dealer always comes prepared. The spread pattern means the killer would have trapped here, though. But there's no second body. He must have found a way out.
Reviewing the evidence collected so far
Batman: The killer made his way up the wall to avoid being overcome. I should follow the route and see where it takes me.
Scan of wall imprint
Batman: Hmmm. There's no way he could reach that ladder... I should review the crime scene to see how he made his escape.
Scan of discarded ladder
Batman: These prints belong to Qing Lu, one of Penguin's top hitman [sic]. Chances are I'll find him at the docks. I wonder what Cane did to deserve this.
Finding Qing Lu
Qing Lu: So you in or out?
Criminal: If Cane's dead like you say, why ain't we heard nothin' bout it?
Qing Lu: Oh, don't worry, you will.
Criminal: Yeah? Why? Was you there when he dropped?
Qing Lu: I'm the one that did it.
Qing Lu: Don't gimme that look. Guy was getting lazy and you know it. It's bad for business. But good for us. Someone's gonna have to take his place.
Criminal: I dunno... I need to think about it.
Qing Lu: Don't take too long. I got a line of guys that would kill for this gig.
Batman arrives at the scene
Batman puts Qing Lu into an interrogation lock
Qing Lu: What do you want?
Batman: Answers. Did Penguin order you to kill Alex Cane?
Qing Lu: I don't think so. If anything, Cobblepot's gonna have *me* killed for doing it.
Batman: Then why?
Qing Lu: I was sick of playing heavy. I figured if Cane, you know, disappeared, I might be able to move up in the world.
Batman: You're not moving anywhere now.
Batman knocks Qing Lu out cold
Batman: Alfred, let GCPD know where they can find Cane's killer. You can forward them all the evidence too.
Alfred: It's already done, sir.
Coventry Fire Casefile Closed
GCPD Dispatcher: Your request has been logged. All available homicide units are out on calls. First one back is yours.