Rob Morrow stars as FBI agent Don Eppes, who recruits his mathematical genius brother, Charlie (David Krumholtz), to help the Bureau solve a wide range of challenging crimes in Los Angeles. From two very different perspectives, the brothers take on the most confounding criminal cases, aided by Don's partner, Terry Lake (Sabrina Lloyd), and new FBI recruit David Sinclair (Alimi Ballard).
Don’s team is charged with running VIP security for a big political rally featuring high profile activist Benjamin Polk. While scouting out the venue in preparation for the event, Don and his team come under heavy fire and receive a message to stay away from Polk during the rally. This overt attempt to scare Polk and the FBI away doesn’t work, and Polk insists on keeping his speaking engagement at the gathering. The FBI then digs in to try and discover who is making the threat, and discover that it’s a man who’d lost his son during a violent riot orchestrated by Polk to gain political street credit in order to further his own career. Furious that his son had been blatantly used as a pawn, the man, Shepard Crater, had come to LA to exact revenge. On the day of the rally Crater sets off a sequence of events to force Polk back to his hotel, where Crater is set to ambush and kill him. Charlie deduces the plot just in time, and David and Colby move in and take Crater down before he can kill Polk. However, after learning the whole story from Crater before they take him down, Colby and David meet with a political journalist and blow the whistle on Polk’s tactics, effectively ruining his political career.
When two FBI agents are killed during a shootout with heavily armed bank robbers, Don and his team must investigate the shooting to determine exactly what happened. The FBI unit involved was headed by Don’s former mentor, Pete Fox, and had been tracking the robbers, know for their extremely violent tactics, waiting for them to pull their next job. The only one of the robbers to survive the gun fight was Jim Wilson, and while he admits to pulling the job and shooting at the FBI, he insists that he didn’t kill anyone. Charlie uses a three dimensional recreation of the scene to prove that Wilson isn’t lying, and as the team starts putting the pieces together they discover that Fox’s team was dangerously inexperienced for the mission they were on. They start looking in to Fox and discover he was under investigation for many conduct infractions, and come to the conclusion that Fox had used the shoot out as cover to eliminate the undercover agent who was putting the case against him together. Don goes to confront Fox and finds him at a gun fight simulator course, where the two of them play cat and mouse with live ammo, and Don ultimately is forced to shoot Fox down.
Don and his team investigate a deadly gambling ring running a high stakes Russian roulette tournament. They get their first big break when a baby monitor camera picks up a live feed of the tournament in progress. The FBI is able to ID one of the participants, Glen Olin, and discover that he has a long history of gambling and that his wife had reported him missing. Charlie is able to find the website dedicated to the tournament, and monitors it for the next live feed, which leads them to the actual location of the game. The FBI burst in and are able to take Olin in to custody, but are forced to let him go when they can’t get any crimes to stick. Knowing that Olin is putting everything he has in to the tournament, including his own life, they put a tail on him which he is quickly able to shake. However, the team is able to put all the pieces together before Olin can play the final round of the tournament. It turns out that a reality television producer down on his luck had created and rigged the game for an accomplice to win, but the accomplice murdered the reality producer so he could keep all the money. The FBI turns up during the final round to take down the accomplice and save Olin’s life.
Don and the team investigate a series of murders which they realize are being copied from scenes out of a soon-to-be-released movie. Also, Larry leaves to embark on his personal adventure.
When the team is mysteriously removed from a routine custodial kidnapping case of a three year old girl, Don and Charlie must work together outside the system to find her. As they dig deeper, their investigation unravels into a conspiracy surrounding the the child and an infamous bio-geneticist willing to murder her to dispose of any evidence that he was involved with a human cloning experiment gone awry.
A woman is killed on a decommissioned air base and when the team investigates, they observe strange almost paranormal happenings taking place that gives the case a decidedly different tone.
During an undercover sting at a computer hackers conference, our agents are outed by a charming, smartass hacker, Augie Harris. Augie agrees to cooperate rather than go to jail, but, ultimately, inserts a malicious worm into the FBI system as a distraction, while he makes a bold move to take over the online black markets. The turf war escalates to murder, and our team investigates the strange world of cyber crime-lords, fraud and spam-kings.
A dedicated FBI agent, Ian Edgerton turns into suspected felon when CI Vincent Costello is found dead the morning after meeting with him, his throat slit ear to ear. Edgerton, not yet convicted, is thrown into L.A. Federal Penitentiary and is Q&A'd by our FBI team, revealing Vincent Costello was key in exposing Victor Salazar, an FBI most-wanted felon who had been running a heroin ring from inside the prison where he had been sentenced for life, the same one where Edgerton is now being held. Costello knew the location of Salazar's bookkeeper, Frederico Garcia who was also sentenced to L.A. Federal and disappeared inside the system. Edgerton goes AWOL and escapes their custody inside the prison, causing the facility to go into lock down. Edgerton takes Agent Colby Granger, hostage, Don Eppes misses his opportunity to take out his old friend and colleague. While Edgerton holds Colby hostage in the Guard Break Room, the team proceeds to negotiate the situation, sending math expert Dr. Charlie Eppes who's task is to find Garcia who Edgerton believes switched his ID bracelet with a number of prisoners to hide inside the prison so Salazar's people could not find him. Time grows short, Edgerton threatens to kill Colby and the negotiating team use explosives to burst through the walls of where he is being held, which is merely a distraction for U.S. Marshall John Galvin who has been working for Salazar the whole time. Galvin helps Salazar locate Garcia and just as he goes to take him out, Don takes Salazar out.
Don and David investigate a 16 million dollar ransom wired to the Cayman Islands and question John Buckley (Ep. 512) who is serving 7-10 years in prison for a bus hijacking. Buckley tips them off that the bad guys responsible for the stolen money is about to hit a jewelry store which to their surprise turns out to be a Diamond Exchange where 26 hostages are taken. With the clock ticking, the bad guys demanding the FBI an escape route out of the exchange, threatening to kill hostages; the FBI must rely on Buckley to unravel the case, who uses this as leverage to shorten his sentence with the DA. They discover the ring leader is Len Maddux who shared a cell with Buckley and stole his strategies. Buckley says they are using the hostages and demand for an escape vehicle as a form of misdirection so that they can escape underground. Yet, once the FBI storms the Exchange, they realize that the Bad Guys have used a bit of "smoke and mirrors" when they find that the masked men inside are employees and that the Bad Guys have changed clothes with the hostages, using the disguise to walk out the front door and taking Buckley with them. David and Liz go to recover Buckley from the trunk of the car and instead find two from Maddux's crew who reveal that the 16 million was going to be laundered through the exchange. Charlie and Amita uncover that the money was converted to diamonds and discover that it was released to an already suspected insider, Lola Sacco who double-crossed Maddux and was inevitably double-crossed by... Buckley, who orchestrated the whole plan and escapes.
When there’s a robbery at the Federal Reserve, the FBI finds D.B. Cooper money. They follow a lead to an armored car driver, killed before they arrive. His Uncle, Roy Till, becomes the lead suspect in a 1971 hijacking. Our guys call on Roger Bloom (Henry Winkler) for his expertise. Bloom tells them that D.B. Cooper asked for two chutes, and they found the body of Eddie Dwyer in a tree. Theory was that Cooper stabbed him and threw him off the plane as a decoy. Now Dwyer’s son, Teddy Angell, is after Till for revenge.
When a string of convenience store robberies targeting scratch-off lottery tickets turns deadly, a California State Lottery Agent enlists the FBI’s help to expose a stolen card-cashing scheme. The team realizes this is only scratching the surface when Charlie uncovers evidence that the conspirators are creating a cryptanalytic attack to crack the lottery’s algorithm used to encode winning tickets in order to predict and intercept the big jackpots.
The agents delve into the world of international arms dealing when they get word of a shipment of weapons moving through the port, supposedly destined for a war-torn region of Southeast Asia. But the stakes get even higher when they discover the weapons are faulty, rendering them even more deadly. They also learn that the guns are intentionally destined for the streets of LA. Meanwhile Charlie and Amita cannot decide on a wedding date. Don asks Robin to marry him for practicality sake and she declines, knowing it is a sign of his unreadiness. In the end they decide that when he is ready, he will romantically propose and she will accept; for now they happily maintain their two household arrangement. Charlie and Amita try to find a wedding date using competing math equations. Ultimately Alan gives them his wedding date October 9th, and he is happy to share it with them. David shows an arms dealer a crime scene with massive deaths, that he has enabled through his dealings of deadly weapons. The arms dealer realizes he cannot contribute to help guns get to the streets anymore and helps the FBI trap a huge arms dealer and find the shipment of faulty weapons.
Don and the team investigate a series of murders where all the victims are men that sleep with prostitutes. DNA evidence reveals that the killer is a woman and that she has a rare blood condition. A database search doesn't produce any leads until Amita thinks to search for partial matches with similar genetic variables; if the killer is not in the system maybe someone in her family is. The search leads to Melanie Bailey the sister of a prostitute who has been beaten and left for dead. The team suspects that she's not working alone. When they track her down in a hotel bar on the hunt for her next victim she refuses to give up her partner. After David and Colby review surveillance footage and talk to the bartender they figure out who Melanie and her partner have targeted. Now they have to get him before he becomes their next victim.
A group of thieves, disguised as seat fillers, spring from their seats at a star-studden Hollywood award show and steal jewelry from the neck, ears, wrists, gowns and lapels of the attendees, then make an organized escape. Charlie finds a pattern to the seating of the robbers, and the choices they made in their victims' jewelry...which all turns out to be borrowed from high-end jewelry stores (a common celebrity practice). The case leads to a South American theft group, high end insurance fraud, and celebrities with more flash than cash. Meanwhile, seeing the size of the diamonds that are part of this case, Charlie begins to wonder if he got a big enough stone for Amita's engagement ring.
Mary, a TV reporter is doing a retrospective news story about 3 men Sean, Devin and Matt who when they were ten years old were kidnapped and raped by the same man, Andy Winslow, their Shop teacher. Overcoming their trauma, Sean, now a successful litigation attorney, and a likely candidate for Mayoral election, and Devin, now a best selling self-help author, have turned their shared experience into success. The third boy/man is Mary’s brother Matt who recently killed himself after a long run of depression and drug abuse. Devin is shot as he is greeting Sean for the retrospective interview. The group uncovers a 4th man, Mike Nash, who Sean, Devin and Matt had been protecting all these years, who was raped as they were. He is also the man that shot Devin; his motive being revenge for him selling a movie based on their story. They had a secret; when Winslow got out of jail Sean and Mike beat and raped him with a bat while Matt videotaped it and Devin waited in the car. Now, all 4 men were being contacted by Winslow who was attempting to blackmail them after discovering Matt had videotaped the crime they committed against him. Turns out, Devin was going to cut a deal and testify against them. Matt would not destroy the tape and killed himself out of guilt. When the FBI confronts Sean, he shoots himself. Meanwhile, Charlie and Anita accept a 6 month teaching position at Cambridge University, thus postponing their wedding. Larry has returned to teaching and is offered a job to work for Kath Berry with Alan at the software company. David uncovers some personality quirks in Colby and Charlie while updating their “in service” reports.
Charlie and Amita’s have an intimate wedding with Larry performing the ceremony. Alan is dead set on moving out of the house now; as he said he would when Charlie got married. Meanwhile, during a scuffle while making an arrest, Don’s gun gets knocked out of his hand, and is stolen. The team’s sole focus now is on locating the whereabouts of Don’s stolen gun. LAPD reports two dead drug dealers in the worst part of town and the slugs from the murder weapon match Don’s gun. The team discovers various social network websites referencing “Cop’s gun”, and a photo of the dead drug dealers. A vigilante gun taking care of what the cops can’t is the message spreading around the websites. The gun is covertly being passed around to various vigilantes around town. The trail leads them to a suspect who has been victimized by a terrifying neighbor who the police have been unable to arrest. They find the gun has been picked up by the family’s 15 year old son who is hoping to fix the problem. Ultimately Don is able to get the gun back from the teen and Ian Edgerton shows up to arrest the terrorizing neighbor who is a fugitive from Florida Sate Prison. Larry and Alan will be renovating the garage into a guest house for him while Charlie and Amita are in England. Resolved in his decision to stay with the F.B.I., Don asks Robin to marry him, and she says yes.