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.
The first season of Travelers has a score of 100% on Rotten Tomatoes based on nine reviews with an average rating of 8.0/10. Neil Genzlinger, writing for The New York Times, described the first season as "tasty", and "enjoyable science fiction", with "some attention-grabbing flourishes and fine acting". Hanh Nguyen, writing for IndieWire, describes the series as "fun and freaky," finding the series' appeal "in how the core group of five travelers adjust to life in our present," noting the "human nature in the travelers". Lawrence Devoe, of TheaterByte.com, called the series "tautly paced and suspenseful" with "well-developed characters", declaring that "Brad Wright has a real knack for creating futuristic series". Evan Narcisse, reviewing the first five episodes for io9, appreciated the moral dilemmas offered by the series premise and the awkwardness presented by the characters' interactions with their hosts' friends, colleagues, lovers, or caretakers: "This is a superhero show in double disguise, offering up clever explorations of the secret identity concept that touch on the guilt and contortions that come with living a double life." Netflix announced that the series was one of its "most devoured" series in 2017.