Don and Agent Weston of the NTSB investigate eyewitness accounts of a mysterious unidentified object flying dangerously close to downtown Los Angeles that has raised concern of a terrorist attack. After Charlie is recruited to help with the investigation,

A truck carrying radioactive material is stolen, and the thieves threaten to set off a dirty bomb in L.A. in 12 hours if they aren't paid $20 million. While Don attempts to track down the truck, Charlie tries to come up with the most likely location where

The city is in a panic as a sniper goes on a shooting spree and randomly kills several people, including a postal worker. The investigation reveals that more than one shooter is at work. As Charlie works the case, he's frustrated by a sniper expert Don br

A strange series of robberies leads Don into a case involving counterfeit money, kidnapping and murder. Don is aided by Secret Service agent Kim Hall while Charlie uses math to analyze fake bank notes and track their spread.

A young girl is kidnapped, but her parents refuse to cooperate with Don's investigation. The girl's father is a mathematician, and the kidnapping may be related to his work on the Riemann hypothesis.

After an engineering student at CalSci is found dead from an apparent suicide, Charlie convinces Don to launch an investigation after he reads the student's thesis that asserted that the architecturally magnificent Cole Center in Los Angeles is structural

Various people in the L.A. area with seemingly nothing in common start to become extremely sick and die on the same day. Don fears bioterrorists may have released a deadly virus into the environment. While he tries to discover whether anyone is behind the

Charlie accurately predicts where a band of bank robbers will strike next. But when Don and his team confront them, a massive shoot-out occurs leaving four people, including an officer, dead. The outcome disturbs Charlie and he retreats into the family ga