Enterprise investigates a stellar nursery with several ships inside. Hailing one, they encounter a group on a pilgrimage to the Great Plume of Agosoria. Every eleven years, one of the protostars emits a neutron blast that the pilgrims consider a sacred event. The eruption is due tomorrow. Archer invites the pilgrims to visit Enterprise. In Engineering, Trip explains the Warp 5 engine to the pilgrims in simple language. One of them turns out to be a warp field theorist. While Trip is distracted with a question, the alien disconnects an antimatter junction. His arm morphs, revealing him as Suliban. As Enterprise tries to go around a plasma storm, a plasma bolt strikes the ship and causes an antimatter cascade that almost reaches the reactor, but is stopped in its tracks by the disconnected junction.
Trip detects the sabotage in the junction, but does not suspect any of the Enterprise crew. Crewman Daniels informs Captain Archer that he believes one of the pilgrims is Silik. In his quarters, Daniels tells Archer he is not a Starfleet officer but from the 31st century. He says that the people who command Silik are from an earlier century, and also speaks of a Temporal Cold War. He comments that Silik prevented the warp core breach and Daniels has been sent to capture him, and asks for permission to tie his Suliban tracking technology into the Enterprise's internal sensors.
T'Pol observes that a power relay is offline; Daniels repairs it by walking through a bulkhead. In the mess hall, Archer studies the group of pilgrims, wondering which one is Silik. Later Archer notices one of the pilgrims' cloaks on his desk. Silik appears and claims that Daniels' group was responsible for the antimatter cascade, and that The Temporal Accord is a lie. He insists that Daniels is a danger to the Enterprise and Archer should help before stunning him. In Engineering, Daniels detects Suliban bio-signs. He evacuates engineering but turns to find Silik pointing a phaser at him. Silik fires.
T'Pol and Trip summon Dr. Phlox to Archer's quarters when they receive no response to their hails. Phlox revives Archer. Archer asks Trip to use Daniels' sensors to locate Silik while he and T'Pol visit Daniels' quarters to study the database that Archer saw earlier. It is gone. Ensign Sato informs them that someone on board used the ship's comm system to send an encrypted message. Silik tries to bypass the lockout codes for Launch Bay 2. Holding Daniels' phasing device, Archer walks through the bulkhead. As they talk, the ship is rocked by another plasma wake. Silik escapes to Shuttle Bay 4, and refuses to surrender the device, so Archer shoots it from his hand. The Shuttle Bay doors open and Silik freefalls to a waiting Suliban shuttlepod. T'Pol hails Archer but he tells her not to follow. Archer then asks his Security Chief, Lt. Reed, to seal off Daniels' cabin.