Gabriel and Riley must rescue a kidnapped member of CyberCom -- the man who invented the chip implanted in Gabriel's brain -- before secret technology falls into the wrong hands.

During an investigation into a suicide bombing at the U.S. Marine base, a discovery is made about a new, chemically undetectable bomb material; Gabriel is unable to finish a task.

Gabriel's chip is hacked, leading to him discovering that Mei Chen is still alive and that she possesses a chip even more powerful than his own.

Riley and Gabriel go on a covert mission in Syria in order to rescue American journalists being held hostage; the truth about Riley's past with her ex-boyfriend is revealed when they are forced to work together.

The daughter of a senator in Mexico is kidnapped by a cartel; Lillian uncovers a connection between her father (Peter Coyote) and the cartel.

Gabriel and the team go to Texas to help contain a deadly, quickly spreading virus and identify patient zero.