Sniper Zero

Synopsis
Sniper attacks are occurring across L.A., but are all the shootings the result of one scattershot marksman or is a fad of sniper killings infecting L.A.? The team need expert assistance in trying to figure that out, and Charlie's theoretical models won't cut it without some first-hand experience to bring them into line with reality.

Plot
Somebody is readying a shot from a rifle and is picking a target. They fire at a postman.

Don and Charlie meet David at the scene and Charlie calculates an approximate location of where the gunman must have been. Ian Edgerton is at the scene. Charlie is only a few feet off due to the assumption that the marksman is a good shot. From his experiences Edgerton believes him to be an okay shot. He believes the shooter will strike again.

Don briefs his team. There have been four victims of a sniper with no link between them. Four different guns or barrels were used to kill them. Charlie and Amita are at the Eppes' house in the garage trying to figure out how good the sniper is. Larry joins them. He's wondering about having kids.

The FBI links the death of the mailman to Wayne Osborne who has a rap sheet, including weapons charges. They raid his home, but he's not there. They ask his girlfriend where he is. She can only point them towards her blue pickup truck.

At the house Alan says that a family friend is looking for a part-time consultant for his business that he could be good for. Charlie gets called to another crime scene. Alan is worried about his youngest son. Charlie tries to alleviate his fears.

Terry and David talk to a woman that was winged outside of a movie theatre. She didn't see the pickup truck around. Charlie and Edgerton discuss where the sniper shot from, giving Charlie insight to the sniper's mindset. Edgerton suggests that Charlie should fire a gun. Terry meets with them on the street. She tells them that Don found Osborne and he has an alibi for the most recent shooting. They come to the conclusion that there are two shooters.

Terry and David interrogate Osborne. He killed the mailman because he was about to marry Osborne's ex. They fish for intel thinking that it's part of a terror campaign run by a militia group. However, Osborne is an ATF informant and has alibis for the rest of the shootings.

Larry bemoans the fact that his morning classes have had low attendance and chalks it up to people being afraid to go out. He also is now considering adoption in his goals to have a family for all of three days. Charlie is looking for a pattern to the shootings. Larry ends up agreeing with Edgerton - Charlie needs to fire a gun to understand how it all works.

The streets are quiet as Don and Terry patrol the city. Alan meets with Don at the FBI for lunch. He probes Don for info about Charlie and tells him how he worries. Don gets called away to another sniper shooting. The victim is a homeless John Doe. Edgerton starts to think that maybe Charlie was right and the sniper is a very good shot.

Amita and Charlie continue to look for a pattern in the data. Even with taking out Osborne's shooting things don't make sense. He starts fresh. This helps him clarify some things. There is an increase in shootings. This leads him to believe that there is an 'epidemic of copycat snipers'. Terry points out that that tracks with infectious behaviour. Charlie uses an example of people painting their houses blue in a neighbourhood after one person starts the trend to illustrate the point. He believes this copycat sniper trend will continue to grow. The FBI start to approach each shooting as it's own individual crime and they solve multiple cases with this new approach. After solving four of seven original shootings, two more are reported. Charlie believes that the first two were done by the some person at the very least as any infection has a starting point. Charlie ends up convincing Don to teach him how to shoot a rifle.

Alan and Larry are playing a game of chess. They discuss Charlie. At the range, Don gives Charlie shooting tips. Sniper Zero is preparing for their next shot.

Charlie plots out the nine shootings on a graph based on the difficulty of the shot. Four of them were very difficult and he believes that those four were done by the same person. Terry talks to the woman who was shot at the movie theatre (one of the four believed to be done by Sniper Zero) to see if she knew any of the other three. Don and Charlie study the photos from the crime scene and Don realises that the commonality between the shootings could be the sniper perches as opposed to he victims and that they could be familiar with the locations. They find that Nathan Crane used to work at two of the four locations. They talk to his mother to figure out his whereabouts as Nathan sets up for his next target.

David links Nathan to the other two sites. They look at his past and decide two potential locations. Terry and Don find his van at one of the locations and call for backup units as they clear the area. Nathan hears the helicopters and looks outside to see his targets are gone...until Charlie gets out of a car. He fires at Charlie. David tackles him to the ground to keep him safe. Edgerton takes Nathan out and Don gets him away from the scene.

Alan is staining the outside of the Eppes' house when Don comes to talk to him about his concerns from the other day.

Main

 * Rob Morrow as Don Eppes
 * David Krumholtz as Charlie Eppes
 * Judd Hirsch as Alan Eppes
 * Alimi Ballard as David Sinclair
 * Sabrina Lloyd as Terry Lake
 * Peter MacNicol as Larry Fleinhardt

Recurring

 * Navi Rawat as Amita Ramanujan
 * Lou Diamond Phillips as Ian Edgerton

Guest

 * Jayne Taini as Marion Crane
 * Don Fischer as Walter
 * Franc Ross as Wayne Osborne
 * Arabella Field as Susan Meyers
 * Heather Lee as Big Mama
 * Nathanael Johnson as Nathan Crane
 * Lamont Holmes as SWAT Leader

Title
A play on the concept of 'patient zero', the origin point of an infectious outbreak, whose identification and quarantine is often vital to the containment of a given condition. Here, Charlie attempts to develop comparable tracking algorithms.

Trivia

 * First appearance of Lou Diamond Phillips as Agent Ian Edgerton.

Goofs

 * The position of Larry's hands changes between shots from in front and behind him during his chess game with Alan.
 * The rifle scope shows the postman's back as he is walking away from the sniper yet the dialogue states he was shot in the chest.
 * When Don and Alan are having lunch, the water bottles on the table keep moving.
 * When Charlie, first draws the x and y-axis. He puts the 'x' on the vertical axis and the 'y' on the horizontal. However, on an actual graph, the x-axis is horizontal and the y-axis is vertical.
 * In the opening scene, heartbeats were heard (inferred to be the shooter's), which sped up as the shot came closer. Pro snipers are trained to control everything (from heartbeats to urination), because the slightest tick can result in a miss.
 * Larry doesn't take his turn in chess before Alan puts him in check - Alan moves twice in a row. Also, from the position shown, there is no legal move Alan could have made to put Larry in check in any event. Finally, in the last shot of the scene, the position of both players' kings and queens have been reversed.

Crazy Credits
[This appears on the beginning of the episode] 1 Sniper, 3 Rifles, 4 Shootings, 4 Deaths