Episode Title: "TWILIGHT"
Production Number: 060
Original Air Date: 11-05-03
The Enterprise is hit by a spatial anomaly, which injures Captain Archer and infects his hippocampus with clusters of parasites that prevent him from forming any new memories. With Archer incapacitated, Admiral Forrest gives T'Pol a field commission to Captain.
After a battle with the Xindi, the Enterprise's warp drive is damaged, and the crew is unable to stop the Xindi weapon from destroying Earth and human outposts including Mars, Alpha Centauri, and Vega Colony, leaving less than 6,000 humans alive in the Galaxy.
The surviving humans eventually settle on the fifth planet in the Ceti Alpha system, far from the Delphic Expanse. T'Pol resigns her Starfleet commission and becomes Archer's caretaker on the planet. Dr. Phlox returns to Denobula and spends almost a decade developing a device that can destroy the parasites infecting Archer's brain.
A Yridian spy follows Phlox to the Ceti Alpha system and relays the location to the Xindi, who attack the Enterprise before Phlox can complete the procedure to remove the parasites, which seem to vanish in the past when they are destroyed in the present. The Enterprise has been enhanced with shields provided by General Shran but the Bridge is destroyed by the attacking Xindi ships. Archer initiates an overload in the warp engine, in order to destroy the parasites retroactively.
Twelve years earlier, Archer awakens in Sick Bay after being hit by the spatial anomaly, but he is free of any parasites, and his memory is not affected. He continues on a new course of events, still the captain of the Enterprise.
Factoid: When Jonathan Archer was 24 years old, he met Margaret Mullin during flight school in San Francisco. The night before he graduated, Archer asked her to marry him, but she turned him down, saying she didn't want to become a "Starfleet widow."
Guest Characters: [Porthos], [Vulcan Ambassador Soval], [Zefram Cochrane]
Alien Races: Xindi-Reptilians, Xindi-Insectoids, Yridian, [Vulcan]
Starships: S.S. Intrepid
KEY: [brackets]=illusions *star=first appearance