Carly loses custody of her son until the trial. Grace is due to die, so Trevor kidnaps her to save her life. Believing he is insane, she flees and is overwritten despite having avoided the accident that would have killed her. Grace and another newly arrived traveler, Ellis, are computer programmers who have fled an anti-Director faction in the future. Ellis has developed a code that is sought by this faction, and has returned to the 21st century to keep it from them. David and Marcy consummate their relationship. However, her condition worsens and Boyd stabilizes her, but Marcy is near death. In the future, Grace was in charge of social media research and identifying the candidates. She wants to correct Marcy's condition with an experimental overwrite. She offers to redirect Marcy's original transfer into the functional part of her brain, saving her at the cost of her 21st-century memories. MacLaren lets Marcy decide, and she decides to speak to David first. However, her condition becomes critical shortly before David returns home, and she is overwritten by her earlier self. Her team introduces her to David.
The team track down Simon (Traveler 0004), a specialist who developed the consciousness transfer technology in the future, who was sent into a host body that developed schizophrenia after arrival. Simon, who set up the Travelers' communications system in the 21st, is haunted by hallucinations of Vincent, who previously convinced an institutionalized Simon that the Director wanted him to next build transfer technology in the 21st.
In an interview with Exclaim!, Nick Thorburn explained that the overhauled lineup was a product of his desire to try new things. "That's important to me ― to be able to constantly try new things. That's why this record's largely informed by electronic stuff like drum machines, sequencing, and programming, which really scales it back from the last record."  Thompson once again left the band prior to the summer 2010 tour, and was again replaced by Aaron Harris.
The team learns that Traveler 001 is still alive in the body of his former psychologist, Perrow, when the Faction tries to capture him/her. Perrow dies but they believe 001 had access to a transfer device (since in the future he helped construct one) and as a result they are unsure where his consciousness now resides. Doubts about their loved ones worsen for Kat (suffering hallucinations and suspicions), Jeff (now, not Jeff and trying to make amends) and David, who is concussed.
Philip is ordered by the Director to attend an "update" with various other Historians, which is where the altered timeline's history is imprinted onto their minds, but it comes with physical and emotional consequences. Trevor tries to help a former football teammate with past trauma. Hall returns from prison and has a new mission assigned to him from the Director. Kat has complications with the pregnancy.
During an update for historians, one of them dies from cerebral overload and is taken over by another traveler. The faction then breaks in and kidnaps the historians. A Blackbox is a device used to extract information from an unconscious or dying person and the team uses one to access a critically injured Hall to ascertain the location of historians. Jeff reaches out to his police sergeant to get his job back and is told to get help from a social worker first. Philip is questioned by the faction. Philip is given time with Kyle as a gesture of good will, who states that he sympathizes with the faction's goal, especially since he just saw another historian die during the update. Faction saves a TELL that Kyle provided to gain his support. Jeff reaches out to David to sign his therapy form for him to get his job back. David agrees to help as a social worker with Jeff's addiction, which the traveler doesn't actually have. Hall is able to relay information from when he was tracking his team's historian showing he ran into a faction team and was shot climbing a fence. He reveals that it was Kyle and Luca from his own team that shot him. Hall is able to show the team the location of the historians and the team is dispatched. While with David, Jeff receives a message to meet up at the location for tactical support. Philip is able to escape before being cornered by Kyle and Luca. Maclaren's team shows up just in time to save Philip and kills Luca and Kyle. The team saves all the historians while taking out many of the faction. Hall is told he saved them all and is able to pass away in peace knowing that. Jeff and Carly reconnect. Philip is seen throwing out his yellow pills that historians have to take.
Found Places Boston Fenway Inn $28+ The Farrington Inn $50+ Hi Boston $52+ Ramada by Wyndham Boston $79+ Comfort Inn Boston $96+ DoubleTree by Hilton Boston Bayside $100+ Best Western Plus Boston Hotel $102+ Boston Lodge and Suites $107+ Hampton Inn & Suites Boston Crosstown Center $122+ Boston Omni Parker House Hotel $125+ Boston Hotel Buckminster $126+ Yotel Boston $136+ The Boxer $138+ Aloft Boston Seaport District $141+