Using a dangerous and untested method of time travel, Cole arrives from a post-apocalyptic future in the present day. His mission is to locate and eradicate the source of a deadly plague that will eventually decimate 93.6% of the human race.
Cole and Railly have finally found peace living in the past. When a mysterious woman with apocalyptic visions of the future tells Cole it's not over, he must do the unthinkable to save the world... and the woman he loves.
Jones comes to the disheartening realization that time travel is humanity's true enemy and that as its architect she needs to be stopped, and so she sends Railly back to the year 2020 with orders to undo all of it.
With the temporal facility on the verge of destruction, Cole and Jones find themselves in the middle of a coup. After a violent encounter ends in an unexpected tragedy, Cole is sent back to 1957 in a last-ditch effort to save humanity while the rest embark on a caravan across the apocalypse to find Titan -- the stronghold of the Witness.
Cole and Railly find themselves at opposite ends of an unspeakable decision. Jones grows suspicious while Railly turns to an emotional ally for advice. All hell breaks loose during a massive fire-fight.
Ramse and Cole splinter to 2007 expecting either a trap - or a final chance to kill The Witness. But when Cole discovers a heartbreaking truth, he’ll discover that the mission was both.
Out of time and in need of answers, Jennifer and Deacon are sent to 1989 to steal a sacred document. Can Railly and Cole get to the Word first before it reveals the one secret they want kept?
Cole's partnership with Ramse is put to the test when they travel back to the 1970s to try to prevent the Twelve from murdering a disturbed Vietnam veteran with a connection to the Witness.
When Cole and Cassie are stranded in 1944, Jones must turn to the person she trusts the least to bring them home -- Ramse. For Ramse, this mission will give him a chance to atone for his sins -- but can he mend the broken relations between Cole and Railly? Meanwhile, Jones visits Old Jennifer Goines to explore the true nature of Time - and the Twelve’s method to destroy it.