Dirty Bomb is the tenth episode of the first season, and the tenth episode overall. It was released on April 15, 2005.
A truck of nuclear materials is stolen by terrorists who intend to use the materials to make a bomb which would then be used on the city of LA. Only Charlie and the Eppes' father Alan can save the city from a small nuclear blast.
Two men leave a roadhouse. One goes to a truck, the other (Ray) goes to a vehicle with radioactive waste. A third man comes to the truck as Ray drives off. The truck won't start. They try to get a hold of Ray, but he doesn't answer.
Four hours later Don and David arrive at the roadhouse and talk with Brent Hauser from the Department of Energy and assess the situation. Along with Terry, they find out that they could be dealing with somebody wanting to build a dirty bomb.
Terry and David discuss radioactive transport with the truck drivers. They think that Ray could be involved with the disappearance. They bring his wife into the FBI to try to find him as he received a large cheque from an unknown source. They find Ray dead by the side of the road off of an anonymous tip. The killers left a second cellphone on him with a message. They have 11 hours to get them 20 million dollars or they'll set off a bomb. They work to figure out where they're going to target.
Terry and David go to talk to a scientist who talked to two people who were asking about radioactive materials.
Larry and Charlie are working to find the target and recruit Alan to help them due to his past as a city planner.
From fingerprints left on a book at the scientist's office they identify Darryl Gerth, a man with a checkered past, as one a potential suspect. C4 was stolen from a naval base.
They bring in Gerth's former foster father and find out that his son, Mark, is in the Navy out of the same base where the C4 was stolen from. Terry and David go to his apartment in hopes of tracking him down. They find the remnants of C4 packaging.
The cell phone gets another call from the bombers. They now have one hour to get them the money or a location downtown will be bombed. Don calls Charlie and for the most likely location. He and Larry can't decide between two sites. Alan intervenes saying that he'd choose Angela Square due to it being an 'urban canyon' which would allow for the greatest damage. Local authorities clear the area with 15 minutes to spare. A bomb goes off minutes later, however it's not a dirty bomb. Since they have no problems killing if they feel like they have to, Don thinks that maybe they're not actually going to use the caesium, maybe they've got it to make the FBI think they will so they will do as instructed.
Charlie, Larry, and Alan decompress after the day's events. Charlie is upset because he was going to choose the other site instead of Angela Square.
The core team looks at businesses at Angela Square to see if they can figure out why Gerth would want it cleared. Due to his history as a thief they look into a company that stores priceless art. They find that a vault has been robbed of $100 million in art. Gerth was identified as a renter in the same building as the art. They also find that he rented a truck under the same alias as the one he used for the office space and to pay off Ray, the dead driver. Using the truck rental information they track down a possible location where they'll be. They breach it to find Gerth, Mark Watson, and a man named Fitchman as well as the stolen art, however there is no caesium to be found.
Don interrogates Gerth, Terry takes on Watson, and David goes for Fitchman. Continuing with Don's earlier thought, they think that there is a possibility that the caesium is still on the original truck not far from where it was taken.
Charlie and Larry have been working on tracking radioactive material, but it will take up to two weeks. Larry describes what happens to people when they are exposed to caesium for prolonged periods of time. As the three suspects aren't talking, Charlie suggests that they put them in a room together and run the Prisoner's Dilemma on them. They put the three men in a room together with Charlie to explain to them what their best odds are given the situation they're in. Watson has the most to lose by going to prison and Gerth has the least to lose. Watson gives them the information they need. There is a fourth man, Carl, with the caesium. The FBI and DoE go to secure the truck. Carl drives towards them, but is sick from radiation poisoning and turns himself in.
The Eppes men leave a restaurant after dinner discussing how Charlie used math to get Watson to talk.
- The term "Dirty Bomb" refers to an explosive, usually a nuclear device, intended to cause maximum levels of radiation sickness and to contaminate the environment as much and as widely as possible. It is in many ways the antithesis of the neutron bomb.
- When Charlie is writing probability numbers on the board he writes 1 then the next number is 1.0. That is an error. They are the same thing/number.
[This appears on the beginning of the episode] 500g Nuclear Material, 20 kg Explosive, 400 threats, 1 Dirty Bomb