Novak has decided to stay at 51 full-time. Stella tells Violet that she's glad Jack Damon is sticking around for a while.

Severide asks Damon what class he was in of his, and Damon backtracks, saying that he never actually took Severide's class. Damon says he was waitlisted.

Ritter confides in Violet that he has overheard Damon's shady phone conversation, and Violet tells him to go to Stella.

Severide is shocked to find several armed gunmen creeping into the firehouse. He hides on the truck, but things take a turn for the worse as the gunmen get in the truck and drive away, with Severide still on it.

Stella immediately realizes the truck is missing. Ritter finds Severide's phone and the crew realizes he is missing.

PD begins an investigation and tells Stella, Hermann, Violet, and Cruz to "hang tight." None of them take that instruction well.

Still hiding on the truck, Severide tries to listen to the criminals to figure out what is going on. He manages to get off the truck and sneak underneath it and then starts manipulating wires in an effort to fix the radio so he can be tracked.

Stella is struggling to handle her worry, and Violet tries to offer reassurance. Ritter comes to Stella to express his concerns about Damon.

Stella immediately confronts Damon about being the last person to see Severide.

Cruz calls everyone over to tell them he's found static coming from the radio and that he's picking up a message from Severide. Kelly was using the truck's wires to send a coded message through the radio.

Severide's movement is noticed by one of the truck thieves. He continues to hide and looks through the truck for supplies he can use to escape. He attempts to run away from the thieves.

The police find surveillance photos of the truck and tell Stella that the truck is headed out of state. Damon is brought in to be questioned by the police about his last conversation with Severide before his disappearance.

Damon denies any involvement in the truck being stolen.

Meanwhile, Severide is still attempting to escape from the location where the truck is being held. He takes someone's cell phone and runs. One of the thieves sees him and begins shooting at him.

Kelly sneaks up behind the thief and tackles him. There is a struggle, and the gun discharges.

The thief is the one who was shot, and Severide does what he can to help him. The other thieves come to see what's going on and hold Severide at gunpoint.

Ritter tells Violet that Dwayne, one of the cops working the case, is his boyfriend.

Novak talks to Damon and tells him not to take the investigation personally.

Stella worries that the theft is abnormal and fears what will happen to Severide.

The injured thief is deteriorating, and the others have tied Severide up so he can't help. He tries to convince them to get him to a hospital, but instead, they shoot and kill their wounded partner.

Severide attempts to make a call from the stolen phone while his hands are cuffed behind his back.

Severide calls Stella and yells at the thieves, trying to secretly get as much information to Stella as he can without tipping anyone off.

The thieves tell Severide that his only chance of getting free is by driving the fire truck for them.

The police get an approximate location and head out to save Severide. The entire crew from 51 goes with them.

Severide sets a small fire inside the rig and tells one of the thieves that it's a problem with the engine. They tell him to pull over.

The crew from 51, along with the cops, are close by when they see an explosion. It is the rig and they locate Severide.

The thieves open fire at the cops and firefighters. Ritter retaliates by hitting the gunmen with the fire hose.

Stella and Severide share a tender moment after the cops apprehend the thieves.

Cruz and Hermann discuss their relief that Severide is okay, and Cruz reveals to Hermann that Chloe wants to go to couples therapy. Hermann offers reassurance and encouragement.

Ritter tells Damon that he was the one who told Stella to question him.

Back at home, Severide recovers in bed, and Stella brings him a drink, but Severide has other activities in mind.