In Season 4, James Cole and Dr. Cassandra Railly set out on an epic quest, traveling further back in time than they have ever been before. According to legend, their only hope lies with a weapon capable of stopping the Witness for good. But they'll soon discover that in order to win the final battle and save time itself, they will have to make the ultimate sacrifice.
The final conflict with the Army of the 12 Monkeys begins when the Witness returns to Project Splinter.
Travelers come face to face with ghosts from their past when they find themselves maneuvering around their own timelines.
Cassie travels back in time to confront a younger Olivia while Cole helps Jennifer find the meaning behind her final Primary vision.
Team Splinter goes back in time to the wild frontier in search of a weapon to destroy the Witness.
A clue to breaking the cycle leads Cole and Cassie to the 1960s.
The team infiltrates a Nazi gala to steal an artifact known as "Die Glocke"; their operation comes undone when French Resistance interferes and an unexpected guest arrives.
Jones sends Hannah back in time to 2007 on a personal mission that could be the key to everything.
Everything changes when the team finally climbs the steps and rings the bell in the Middle Ages.
The beginning of the end approaches as Cole and Cassie embark on their final mission.
The final battle against the Witness as the fate of time and mankind hangs in the balance. All the pieces finally come together to mark the end of the beginning.