Traffic is the fifth episode of the third season. It was released on 20 October 2006.
Charlie and the team grapple with the concept of 'randomness' while trying to find a killer who is seemingly targeting drivers on the freeway.
A man, Jeff Kinkirk, and his sons are travelling down the freeway. He gets shot as they go along and the older son takes the wheel from the passenger side to try to stop them from hitting anybody or thing. They come to a stop before they hit a wall. Charlie is giving a lecture on chance and luck.
Don and David are at the hospital talking to Marla, Kinkirk’s wife. The doctor comes up. He is stable, but there are complications. Don takes the boys off to the side and David stays with her to get the news. Don finds out what happened from the boys. Peter, the younger boy, thinks he saw a white truck right before Kinkirk was shot. Don tells them that their dad is going to be ok. There have been four deaths associated with the seven freeway attacks. Don feels guilty for telling them that their dad will be ok.
Colby can’t find any motive to attack Kinkirk and David says there are no witnesses or tips that help. Megan doesn’t think that it’s the seven attacks are the work of a serial killer as none of the MOs are the same. None of the victims fit a clear pattern either, they come from all demographics. Megan believes that it could be the work of people trying to copy the earliest attacks. Charlie thinks that there is no pattern – they could be random. Don wants to pursue each attack as an individual crime.
Megan doesn’t chalk the attacks up to road rage. Peter thinks he also saw the same white truck near his home. This truck has a bobble hula dancer. She thinks it opens up the possibility that Kinkirk was stalked before being attacked. Don gets her to work that angle, but he believes that the wife may be keeping something from them.
At the hospital Andy, Kinkirk’s older son is catching him up on the daily goings on of the family. Don joins them. The doctors were able to get the bullet out of his brain. He takes Marla out of the room to talk to her. He asks about the truck. She doesn’t know of anybody that would want to kill Kinkirk. He tries too hard to be nice.
Megan is looking into the truck, but is also trying to find a pattern to the attacks. David and Colby tease her saying that ‘Professor Eppes wouldn’t approve.’ She explains to them that none of the attacks were linked to normal road rage causes at all which is odd. There should be some that do if it were truly random. She wonders if something can be too random. Megan goes to the Eppes’ house and asks Charlie about this. It could be hidden variable theory, but he doesn’t think that it’s a factor here.
The next morning David comes up to Colby who has just gotten through a bunch of trucks on the list. David has a connection between two of the victims he wants to look at. They go to the same carwash. One, Raines, was killed two weeks after he got into an argument with one of the employees. Don sends them to look into it. They ask for Calvin Oates who runs when he sees them. The manager uses a bat to help them apprehend him.
Megan interrogates Oates with Don and David looking on. He was working when Raines was shot so they don’t think it was him. David gets a call. There’s been an eighth attack. David and Colby are on the scene. Somebody dropped a cinderblock off of a bridge onto a moving car. Due to the timing of the attack there had to be some premeditation, though they don’t know if the victim was targeted or unlucky.
Charlie meets with Larry. He sees a pillow on Larry’s office couch. He’s been living in his office. Charlie makes some judgements about it and brings up Megan. This leads him to talk about Megan’s question from the night before. He thinks it’s funny, but Larry doesn’t see how it is. He finds the freeway attack case to be kind of weird and makes Charlie rethink the case.
Megan thinks she found new attacks. There were no deaths or injuries so they weren’t reported to FBI, but they still exist. Charlie comes in and apologises to her – she was right. After looking at the timing of the attacks she believes that the suspect is using different MOs to make it look like multiple people are doing the attacks. She believes them to be a serial killer as the attacks are becoming more and more violent and frequent.
Colby finds that five of the 13 victims were involved in serious injury accidents in the last two years. They start to look into them. Alan talks to Charlie about the safety of the roads. Don goes to see Kinkirk who is now awake. He was the only witness to an accident where a child was hurt and gave a statement to the police. The child’s father had run a red light, but the father denied it. The insurance company went with Kinkirk’s account. Megan finds it weird that the suspect doesn’t want to watch all of their victims suffer (a common thing for serial attackers/killers) and doesn’t need to kill every victim. She believes that they – or somebody close to them – had been hurt in an accident.
Don goes to Charlie to get help narrowing down their suspect pool. They discuss their relationships as well as Megan and Larry’s. They get back to talking about the case. Charlie needs some information from the FBI, but also needs to get a bunch of traffic information.
10/13 of the victims were involved with traffic incidents and they are no closer to finding a viable suspect. Megan worries because a 14th attack is due. Amita is working on the case when Larry comes in in pain, probably from sleeping on his office couch. Charlie joins them with coffee. Amita is looking at traffic anomalies. They notice that after some of the attacks traffic gets backed up in a specific section almost like somebody was trying to create an escape route. A car is sticking out of the road. Drivers go around it angrily until a cop car shows up and finds a woman in the front seat shot dead.
She is Catharine Craiger who works for the city of Bellhaven. This attack would be the second close-range gunshot in the series of attacks. Megan is thinking it’s the same person, but they aren’t afraid to repeat themselves. David can’t find any evidence that Craiger was ever in an accident. Colby gets off the phone with her boss. Two years ago she turned down a petition to put up street lights at a blind intersection, meaning she wasn’t directly involved with an accident, but didn’t prevent any from happening either. An accident happened six months after the petition was denied. Only one person of the four people involved survived. Megan thinks he is a good candidate for the attacker. David and Colby take a team to bring him (Brennan Sommers) in.
Don interrogates him. Sommers doesn’t know who Craiger is. He’s in group therapy for anger issues, but due to a physical condition he wouldn’t have been able to have committed the attacks and no weapons he owns can be found that fit the crimes. Charlie has something. He briefs Don, David, and Colby. They check out various routes that Charlie, Amita, and Larry have identified. David and Don talk to a crossing guard at a corner. He saw a white pickup truck speed up to a light that had just turned red, but then turned green after a couple of seconds on the day of one of the attacks. He didn’t see the driver, just a random white guy with sunglasses, but it had something on the dashboard. The suspect has found a way to tamper with the traffic lights.
Charlie sees Larry. He’s supposed to be at a symposium, but he’s by the pond. Charlie is worried about him, but while he appreciates the concern, Larry doesn’t think there’s anything to worry about.
At the FBI David shows a device that can cause traffic lights to change that are only legal on emergency vehicles. These devices leave a trace that they can search out and from there they can look at traffic cameras to find their suspect. David and Colby follow up on Charlie’s findings. They think they found the right guy, but they don’t have a licence plate. There is a sticker on the back window for Head Trauma Survivors United, the group that Sommers is a part of. They take a look at the members of the group. Aside from Sommers there are eight members of the HTSU that are there due to traffic accidents. Two of them have white pickups and of those only one is a man – Mitchell Mackenzie. Two months after he joined the group the attacks started. Megan talks to the man who runs HTSU. Mackenzie talks about everything in group sessions except for the freeway attacks. They get a hit on his credit card. David and Colby take a team to bring him in. Mackenzie was just about to grab a rock from the bed of his truck when he hears sirens and makes a run for it before getting cutoff by LAPD and the FBI team. He admits to the attacks. He feels he makes things right for the people attacked.
Don is sitting in the living room at the Eppes’ house alone in the dark. Alan sees him there and they talk. He thinks Don should take some time off. Charlie comes home. He shows Don that yes, there was a pattern to the freeway attacks in that Mackenzie was the one who did them, but he didn’t start them. The hit and run driver did when he injured Mackenzie and they got away with it. Much to Alan’s dismay he gives Don the file from the case and they start to go through it.
In the scene where Don is throwing darts and talking to Charlie, a green ball is visible on the shelf behind him just next to a bowl of what appear to be gum balls. Later in the same scene when Charlie walks away from the chalkboard and to his laptop, the green ball is now on a lower shelf.
At the beginning of the episode when the father becomes unconscious, the older son pushes his leg against his fathers to move his foot off the gas pedal and onto the break, but in the very next shot his leg is nowhere near his father's leg.
In the big 'reveal', the suspect's white truck has a sticker with 'HTSU" in the rear windshield that is seen on the traffic camera. When the suspect is caught, several shots of the rear windshield show the absence of said sticker.
[This appears at the beginning of the episode] 12 Million motor vehicles, 9,096 Miles of Freeway, 5,339 accidents, 7 Freeway attacks