In the series premiere, Don races to capture a serial rapist who has begun to murder his victims. Charlie is recruited by Don to help track the killer. He creates a mathematical equation to identify the killer's point of origin by working back from the crime scene locations. Charlie's obsession with the case leads him to seek the insight of his colleague, physicist Dr. Larry Fleinhardt. Meanwhile, their father, Alan, is pleased to see his sons working together but fears their competitive nature will lead to trouble.

After a series of bank robberies, Don recruits Charlie to help chart the next robbery location, only to overlook the thieves’ true motive.

When people start mysteriously dying in Los Angeles, Don and his FBI team are called in by the Public Health Service to determine if it is an act of bio-terrorism. Applying Charlie's knowledge of the mathematics of diseases, they track the virus not only to stop it, but also to find its point of origin. Once they determine who is responsible and why, they are surprised by the suspect’s motive. Meanwhile, Don is surprised to learn that Charlie has been keeping a secret from him. CCH Pounder guest stars.

Charlie convinces Don to investigate a student’s suicide in order to make sure that it was not murder.

Don needs Charlie's help to find out why the daughter of a mathematician is kidnapped.

While investigating a deadly freight train accident, Don and Charlie discover a shocking culprit who is on a mission to diminish public confidence in the railroad system.