27 years after a virus wipes out most of humanity, scientists send a man back to 2015 to stop the plague from ever happening. Cole's only lead is a virologist, who knows the dangerous source of the outbreak.

Cole, Dr. Railly and Aaron strive to stop the virus from being deployed as a bioweapon in Chechnya.

Forces come to a head when Ramse does what it takes to protect his newfound family, leaving Cole to deal with the aftermath.

To save the last Primary, Cole must turn to a mortal enemy. Plus: Jennifer Goines, radical revolutionary?