Grant MacLaren and his team find themselves in FBI custody with no means of escape, while a mysterious new traveler reveals secrets to his psychiatrist.
Philip makes an unexpected connection, Marcy helps David cope with his trauma, and MacLaren discovers a shocking truth that Kathryn has been hiding from him.
A deadly disease is spreading around the world, and the travelers must get to the bottom of where it came from and how to stop it, before it's too late.
After receiving an unusual message to attend a court proceeding, the travelers find that one of their own is on trial for conspiring against The Director and interrupting the Grand Plan.
Philip's timeline receives an update with some unwanted side effects, Trevor makes a disturbing discovery about his host's past, and MacLaren deals with the return of a traveler he thought had gone away for good.
While MacLaren, Carly, Trevor, and Philip work with another traveler team to protect a child important to the future, Marcy takes measures to remember her past life – but uncovers more than she bargained for.
In the season finale, the travelers must follow the rules of a madman in order to rescue their kidnapped loved ones and ensure the traveler program isn't exposed to the world.