When an ATF agent is found dead under unusual circumstances, Don wants to take the case, which revolves around an elaborate bank robbery, after he learns the victim was his former girlfriend. He then becomes quite introspective as he realizes the impact his career has had on his personal life and decides to turn his attention toward a new woman.

Don and the team attempt to figure out what happened when a Chinese interpreter turns up dead.

$50 million dollars in medical relief is up for grabs after the shipment is stolen. But there's a catch--someone other than the FBI wants to recover the shipment. Don and the team find themselves pitted against blackmarketeers in a deadly race for the supplies.

Don feels responsible for a life lost. The victim was in the Witness Protection Program, but she wasn't the only one keeping secrets...what is Don hiding?

Don runs into Robin Brooks during an investigation concerning informants and a chess master.

Don's team helps Agent Bloom, a veteran with the FBI, track down a con man who has eluded Bloom for years. Meanwhile, the final decision on Charlie's clearance is handed down, and it doesn't just affect Charlie. Don's job is on the line as well.

Don and his team must race to save the hostages being held on a hijacked bus.

Don and the team are sent to look into a series of bank robberies and soon name former FBI Agent Roger Bloom as their lead suspect.

The team investigates a decommissioned air base after a woman is found dead there, but their investigation is interrupted by paranormal happenings.

Charlie meets his mathematical equivalent when lottery agent Jane assists in the investigation into a complex scam that involves thefts of unsold lottery tickets.

The Numbers team tracks a serial killer who targets johns.