Cut to a security guard walking into an office. His name is James, and he gives "Miss Miller" her keys, left in the lock "again." The two flirt briefly, then he gives her a packae. He returns to his desk, where he's shot by an intruder (after being asked his name and answering) who is leading a team of people behind him. He kills more people on the way to the server room, where they compromise the system, planting what looks to be an electronic bomb behind them and leaving.
Kennex and Dorian tease each other back and forth in the car before picking up a homicide call that brings them to the office building. There are already a number of police officers onsite, and the security cameras have been damaged (although Dorian can access some footage; he sees the killing of the security guard and sees the group of intruders going to the 25th floor, even though the quality of the footage is poor and it's difficult to identify anyone. Kennex tells one of the cops to evacuate the building because the perpetrators are still there. The elevator has been killed so Kennex and Dorian head up to the 25th floor by stairs.
In the office, the gunmen have rounded up all of the employees except a woman in Miss Miller's office, who is hiding under her desk. The lead gunman finds her there, asks her name, and when she tells him Jenna, tells her to join them in the other room. She does. Shortly after that, the gunmen set off the bomb, which blows a hole through floors and ceilings down to the lobby, leaving behind a hole crackling with electricity.
Back at the police department, Kennex and Dorian are heading back up the stairs, telling Captain Maldonado to jam signals in and out of the building. When she starts to object, he pretends he can't hear her and hangs up. She jams the signal, cutting off communication around the building. The lead gunman says this is predictable.
With communication cut off, Dorian begins to take phone calls that can't get out of the building. One such call is from a woman named Paige, who is apparently Jenna's sister. She's calling from a utility closet on the 25th floor, where she sees the gunmen kill someone and drag the body out.
On the ground below, the police are greeted by the man's body, thrown from the 25th floor; pinned to his shirt is a note to stay out.
Back at HQ, Maldonado sends a drone up with a comm attached to negotiate with the hostage-takers. The gunman says that they have demands; that they want the snipers removed and the cops outside removed; they want three vehicles and a fission igniter--military-grade technology she can't authorize. He tells her that she has 43 minutes to comply; her technology identifies him as Lucas Vincent of the Holy Reclamation Army.
On the phone, Kennex asks Paige to tell him how many hostages and hostage-takers there are. She blames herself for her sister, who is visiting from out of town, being in danger. He tells her that she's not alone; that everything is going to be okay.
Back at the station, Maldonado doesn't know what to do because there's no way she can get a fission igniter; Rudy Lom (the tech guy) says he can make a fake convincing enough to pass the initial scans but that they'll be out of luck if Vincent tries to use it right away; she tells him to get moving on it. Stahl provides exposition for the audience by running down the Holy Reclamation Army--anti-western terrorists who aren't afraid to kill or die to get what they want--for the Captain.
On the fourteenth floor, one of the terrorists starts shooting at Dorian and Kennex from above; they return fire and the terrorist takes cover on the fifteenth floor, where they enter to look for him. After a couple of close calls, Kennex uses his cell phone as a distraction and manages to kill tag the shooter, but he's still alive and shooting elsewhere. Dorian has taken him out but was shot in the head in the process; he's got a piece of technology he took off the terrorist. Dorian can identify the corpse, who at first he thinks is a member of the HRA. He figures out that he's wearing a device that alters his appearance, though, and really he's a low-level thug just impersonating a terrorist. He also figures out that he's been damaged by the bullet and won't be able to walk soon.
Dorian figures out that there are seven "facemakers" in the building. Kennex has some tools and is going to try to fix Dorian. As he does so, he disconnects something in Dorian's head and Dorian goes offline. While Kennex keeps trying to fix Dorian, he gets a call from Paige. Just as Dorian comes back online, someone comes into the room, telling them about the two cops; he's been shot, and tells them that he was separated from the other guy.
Vincent calls Maldonado, telling her that he's killed two cops downstairs and that he's upset she sent them; she tells him she doesn't know who those cops were. Paige tells Kennex she's going to join her sister in the crowded room while the terrorists are in a corner office, hoping to blend in quietly, and she does.
The fake fission igniter is sent up via a drone just as Kennex and Dorian find their way into the 25th floor. Paige tells the gunmen she needs to use the bathroom and he gives her thirty seconds; she still has her phone on and connected to Kennex, and adds it to the pile of confiscated ones on a desk. Kennex overhears Vincent telling his men to alert the other group to get started; Kennex and Dorian figure out that if there's another group it must be outside the building, and that the device Dorian couldn't identify after being shot but before being repaired was some kind of point-to-point communications system to overcome the jamming.
One of Vincent's men asks him about the possibility of a tracker in the igniter. Vincent says they're not going anywhere with it, so it doesn't matter. Kennex and Dorian figure out that the whole thing is a diversion for a heist at a precious metals facility nearby. They set another "light bomb," and will each take three hostages for insurance and leave the rest in the room with the bomb.
Dorian tells John that if there's imminent danger, he will go up through the elevator shafts, but that Kennex can't; he's not designed to do incredible feats of strength and agility. Working his way to the 25th floor quickly, he sees the light bomb and can identify the bad guys (or at least who their faces say they are). Dorian takes out all but two of the gunmen, but Vincent is about to kill him when Kennex shows up wearing the false face of the one Dorian killed downstairs and takes out the last two. Dorian deactivates the bomb; Kennex calls in the heist to Maldonado; the palladium heist next door is averted when alarms start to go off.
Outside after the fact, Paige meets up with Kennex and Dorian to thank him for their help. Maldonado accosts him with paperwork and Rudy goes after him for using chewing gum to fix Dorian. Kennex takes Dorian out for noodles instead of staying for the abuse. On the way, Dorian confides in him that he was terrified of dying when the gun was to his head.