Lord Howe is way out in the middle of the Tasman Sea, a two-and-a-half-hour plane ride from Sydney. It takes days by boat. However you get there, the journey is worth it.Named after a British admiral, Lord Howe is the world’s most southerly coral island. About 350 people call it home, many descended from families who settled there in the 18th century.
Many of Travelers' ancestor companies, such as St. Paul and USF&G, are technically still around today, and still write policies and accept claims in their own names (under the overarching Travelers brand name). As is typical of most insurers in the United States, Travelers never dissolved the various companies it acquired, but simply made them wholly owned subsidiaries and trained its employees to act on behalf of those subsidiaries. This is a common risk management strategy used by U.S. insurance groups. If any one company in the group gets hit with too many claims, the situation can be easily contained to that one company (which is placed in runoff and allowed to run its policies to completion), while the remainder of the group continues to operate normally.
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.
Travelers transfer into a cult preparing for mass suicide. MacLaren's team, the cult, and many other travelers, including senior engineer Bloom, meet at the antimatter facility. Bloom reveals that the future has been subtly rewritten and is not as united as it once was. Dosed with antitoxin, they release a toxic cloud to force a local evacuation. Gleason interrogates Delaney until MacLaren returns her to the facility and explains the nature of travelers. Gleason discovers Delaney's escape and prepares to return to her lab. Using the antimatter to power an x-ray laser, the travelers intend to deflect asteroid Helios 685, saving millions of lives and preventing the environmental catastrophes and devastating wars that led to their dark future. Deflecting Helios has been the Director's main goal, even though it could possibly prevent the travelers' own births in the future. Gleason leads an assault, killing most of the cult travelers and Bloom before she can fire the laser. However, travelers transfer into his soldiers and eventually into him, sacrificing themselves to complete the mission. The traveler within Gleason fires the laser while MacLaren and his team save Delaney from the antimatter explosion on Bloom's orders. MacLaren is unsure of the mission's success, as his team remains in the present.
A family of four are about to die in a car crash when the mother, father, and son become travelers. Charlotte, the daughter, retains her identity when the team's historian's transfer misfires, so MacLaren sends her to stay with her grandparents until the others complete their mission. Trevor, Carly, Marcy, and Philip are abducted and interrogated about the future until Carly kills their guard. David alerts MacLaren when Marcy does not come home, who is able to find and rescue the team with Officer Boyd. MacLaren was forced to cancel the team's mission with the family team, and Carly speculates this was their unidentified captor's goal.
Kathryn confronts MacLaren about an affair she believes he is having, leading him to end his relationship with Carly. Charlotte, the misfire historian, is overwritten and murders her team. She attempts to assassinate Grace, but Trevor stops her. Grace reveals that the anti-Director faction was responsible for the team's abduction. Charlotte is shot by Jeff while attempting to kill Carly. Ellis reveals that he has built a quantum frame that the Director, an advanced AI, can use to travel to the present to escape the faction. David is held at gunpoint by another assassin but is saved by Marcy. The team arrives at the farm where Trevor has received a text to destroy the frame. Boyd reveals she received an order to kill MacLaren and holds him at gunpoint; Carly later reveals having been given the same mission. Assassins surround the farm as Ellis shoots Trevor to keep him from harming the frame. Grace jumps in front of Trevor and is shot as well. Ellis shuts down the perimeter shield in the hope that the Director will help them and delivers a message to destroy the frame shortly before he dies. It is revealed that the people surrounding them are not anti-Director assassins, but FBI agents led by Forbes.
Three high-ranking Travelers are sent back by the Director to put Grace on trial for violating protocols, overwriting a person who was not assigned to be her host, and sabotaging the Grand Plan. Mac and the team must give testimony at the trial that will determine if she should be overwritten or not. Meanwhile, the Faction is trying to replenish its numbers by overwriting people with the stored minds in the Quantum Frame. It transpires the trial was staged by the Director to flush out a Faction member from within the three Travelers judging Grace, which it successfully does, this leading to Mac's team securing the Quantum Frame.