Troy Argall

Don and his team must stop a sniper who goes on a killing spree in Los Angeles. Racing against time to find the sniper, Don calls in Agent Edgerton (guest star Lou Diamond Phillips), a senior Sniper Instructor from Quantico, to assist on the case, causing Charlie to feel insecure about his role as special consultant to the FBI. Feeling animosity towards Agent Edgerton at first, Charlie learns from him that human behavior could make his mathematical equations useless. Instead, Edgerton encourages Charlie to get inside the head of the killer.

After two teens are found murdered, the investigation leads Don and his team to uncover a dangerous counterfeit money ring. Charlie is called in to use his mathematical expertise to pinpoint the location of the counterfeiters by analyzing the dispersion of the bogus money. In the process, he also discovers a surprising connection to the disappearance of a local artist. Meanwhile, Charlie realizes how little he knows about his brother when he meets someone from Don’s romantic past.

When a recent murder bears a strong resemblance to a murder case he closed a year ago, Don questions whether he sent the wrong man to jail. As a favor to Don, Charlie examines the old case and finds flaws in the fingerprint and eyewitness systems that put their reliability into question.