A woman abruptly wakes up on the ground. She is disoriented and gasping for air. She gets up and notices her neck is bleeding. She faces her face and grabs her gun from a drawer. She goes to the door and opens it. A huge explosion occurs, throwing her body across the room, and engulfing her body and room in flames.
At Booth and Brennan's house, Booth and Sweets enjoy watching a martial arts film. Brennan feeds Christine and doesn't understand the movie. Sweets gets a call-the apartment he was interested in is still available. Sweets is going to move out. Booth and Brennan are a little skeptical that this move will actually work out. Booth gets a call-there's a body in a shed in Virginia. Sweets is going to watch Christine. Brennan is going to miss the free childcare.
On the scene, everything is charred including the body, which has no head. Brennan determines the victim is female in her mid-thirties. Booth notices ammunition and explosives all over the place but there was only one gun. Brennan notices that the victim's vest didn't burn. Cam finds the victim's head in the toilet.
On the platform Brennan and Daisy examine the victim's two gunshot wounds the victim has. Daisy asks if Sweets is really moving out of her house, Brennan tells her that Sweets is in fact leaving the house. Back to the body, they examine the fire exposure the victim suffered. Cam comes to the platform to inform them that the victim is Deanna Barbieri, ex-military. Brennan determines cause of death was the slugs hitting the victim's inferior vena cava. Brennan gets a call-she has to go.
Brennan meets Booth at the diner for lunch. Booth tells Brennan to prepare to help Sweets leave the house when his apartment falls through. Sweets enters the diner to tell them that he will be out of the house within a day. He tells them that the victim was discharged from the military for a fight with another marine. There is a pattern of misconduct. Sweets tells them that they need to talk to the other marine, Carlene Blayney.
Hodgins found a mixture of phosphorous and magnesium, which is used as an explosive, called Dragon's Breath. It creates a fifty-foot flame and lasts three seconds. This means that the same shot the killed the victim could have started the fire. Hodgins grabs a gun, Cam comes up hesitant. Hodgins shoots the gun anyway into a dummy-it starts a fire. It proves that the shot that killed the victim also started the fire.
At the FBI, Booth talks to Carlene Blayney. She used to friends with the victim until one day she started talking about the end of the world. Carlene didn't agree with her so they started a fight. Deanna believed that society was going to fall apart. Booth has phone records showing that Carlene called Deanna eight times in the past few months. Carlene was calling to apologize but Deanna fell off the grid and didn't know where she was.
On the platform, Daisy shows Brennan a remodeled injury that is less than a year old. Daisy can't figure out what caused the injury. Brennan examines it and realizes it is a cannonball. Brennan wonders how someone who fell off the grid suffers an injury like this and still gets excellent medical attention.
Hodgins has taken samples of the injury and found cast iron and lead-which could mean it was in fact a cannonball. Hodgins has pulled that Civil War cannonball press that was found-the victim made her own cannonball. Hodgins wants to test his theory. Angela comes up and tells them that the measurements of the ball matches the break on the victim's leg. Hodgins stills want to test the theory.
At the FBI, Booth tells Sweets about the cannonball. Sweets gets a call about his renter's insurance. Booth is surprised that this move is still going through.
Daisy shows Brennan the pitting she found on the mandible. Brennan examines it: it's caries sicca caused by the lesions of syphilis. Cam comes into the Bone Room to learn about the syphilis. They believe the victim didn't know she had the disease. Cam tells them that there were samples of benzodiazepine in the victim's system.
Angela informs Cam that she did a search to find anyone near the victim who was buying lead in large quantities and she found: Dr. Fred Dumaski. The girls see Hodgins preparing a Civil War cannon. Hodgins shoots the cannon into a mattress. All the calculations match up that it was a cannonball. Hodgins is happy that it is a match AND he got to fire a cannonball.
Booth and Sweets talk about Dr. Fred Dumaski aka Dr. Apocalypse. They look at his website. He is a survivalist and a "doomsday preppers." There's a video on his site about how to make a cannonball. Sweets analyzes survivalists: they are tight community who are defensive and suspicious when it comes to government. Booth has records that Dr. Dumaski recently bought ten acres of land and he also spent a lot of money towards a company called, Safe Harbors, which specializes in survival bunkers.
Booth and a FBI Swat Team scout through vacant land. They look for the bunker. Booth sees something. The team looks for booby traps. They reach the bunker but it has a time lock on it. They blow it up. Through the smoke emerge a goat and some animals as well as Dr. Apocalypse and three other survivalists.
In the Interrogation Room, Dr. Dumaski admits he knew that Deanna would be an asset to the prepping group. Booth asks about how Deanna broke her leg. He says it was an accident and an opportunity to showcase his trauma care. It brought the group together. Booth notices a rash and swelling on the doctor's arm. He tells them that it was from a shot for a venereal disease. Booth tells him that they knew that Deannna had syphilis. Dr. Dumaski says that his wife knew about everything.
Hodgins shows Brennan a list of items that were in the bunker. There was phosphorous and magnesium on the list, which means one of the preppers, is most likely the killer.
Booth and Sweets analyze the other preppers in the FBI Conference Room. There is Delores Dumaski, the doctor's wife. Dennis Bukovac, a retired minister. Milo Miles, a mechanical engineer. They need to talk to all of them.
Angela and Hodgins go over scorched debris that she can identify from the fire. There's a screwdriver. Hodgins realizes that it would be made out of beryllium, which has a melting point of 865 degrees Celsius. The shell casing is made out of brass, which didn't melt and has a melting point of 905 degree Celsius. Hodgins tells Angela that in these temperatures a human body would have been ash meaning that the fire burned for a shorter period of time. Hodgins adds that no one in the bunker could have murdered Deanna.
Sweets visits Daisy in the lab. Daisy doesn't believe that anyone in the group could have killed her. Sweets doesn't understand it, Deanna was killed around 8:30 a.m. but all the preppers were locked in the bunker by then. Sweets needs to have Booth look at the bunker again. Daisy takes a moment to tell Sweets how wonderful he is, Sweets feels the same about her. Daisy notices something on the bones.
Brennan shows Cam what Daisy found. She thought it was pitting but it appears to be a syringe, which could explain the drugs in her body. However, the puncture is a very large needle. Hodgins is going to swab it to see what particulates he finds.
Angela got the bunker plans from Safe Harbors. Hodgins is hoping they find an escape route that can override the time lock on the bunker except Safe Harbors wouldn't tell any of their plans. Angela has made a model of the bunker so that they can digitally walk through it. The bunker is made out of Category One steel. However, there are riveting that are used that wouldn't be used with that type of steel which means there is a section of the frame that isn't Category One. They need to find this section to see who was sneaking out.
Cam tells into Brennan's office to tell her it was a 12-gauge syringe used on Deanna, which is usually used on animals. The preppers raise animals for food. The items that were logged from the bunker was Benzodiazepine for veterinary use. Therefore, it had to have been one of the preppers.
Angela and Hodgins try to figure out how someone would have escaped. They are not having luck. Booth calls he needs to see the evidence from the shed-he thinks he knows how Deanna was killed.
Hodgins cannot believe that Booth came to the lab. Booth lays a few items out for Hodgins to look out. Booth tells him: booby-trap! Someone drugged her set up a booby-trap, and locked themselves in the bunker so that when Deanna opened the door it was set off. As usual, Hodgins wants to conduct an experiment to make sure this theory works.
Hodgins makes a mock booby-trap with the front door of the Ookey Room. Hodgins has replaced the Dragon's Breath shell with gelatin. Booth gets in front of the trap to check the trajectory just as Cam opens the door. Gel goes flying all over Booth. Hodgins cannot believe what just happened. Cam apologizes.
Booth brings in Milo Mills who's engineering background would help making a booby-trap. Milo analyzes it and says Delores would be able to as well. Milo tells them that everyone would teach each other their skills incase someone became incapacitated. Milo tells Booth that as preppers you cannot wash as much to save water, however, Delores always practices that. She would have residue from making the trap.
Booth and Brennan bring in Delores next who's hands are definitely dirty. Brennan can't find traces on benzene and toluene. Brennan brings out an acetylene torch. The burst of flame shoots out of Delores' hand when Brennan puts the torch to it. Delores comes clean-the object was to survive and how can you survive with someone aggressive, overbearing, and dishonest like Deanna.
Back in Angela's office, Carlene Blayney comes in. Angela has reconstructed a letter she found at Deanna's bunker. Angela tells her the letter will make her sad but she will get some happiness from knowing how Deanna really felt. Carlene is touched when she reads Deanna's words.
Back at Booth and Brennan's house, Booth wonders if they should start preparing for the end of the world. Sweets comes down with the rest of his belongings. Brennan pours champagne and they toast Sweets' next step. There's a knock at the door-it's Sweets' new roommates. They are two beautiful females. And with that, Sweets is gone and it's back to just Booth and Brennan.