One Son - Plot

Plot

Continuing the narrative from "Two Fathers", Cassandra Spender (Veronica Cartwright) demands to be killed by FBI agent Fox Mulder (David Duchovny). Before Mulder can do anything, the front door is smashed open by a group of people in hazmat suits, led by Diana Fowley (Mimi Rogers). Mulder, Cassandra, and Dana Scully (Gillian Anderson) are taken to a CDC facility at Fort Marlene. Fowley tells the agents Cassandra Spender is carrying a contagious organism, and that she was called in by her son, agent Jeffrey Spender (Chris Owens). Meanwhile, Alex Krycek (Nicholas Lea) reports on Cassandra's escape to the Syndicate, saying that the alien rebels want Cassandra kept alive. Regardless, the Syndicate decides to turn Cassandra over to the colonists, and save themselves by commencing colonization.

At Fort Marlene, Mulder runs into the sickly looking Marita Covarrubias (Laurie Holden). Marita tells Mulder that she was subject to experiments by the Syndicate to create a black oil vaccine and that the colonists will begin colonization if they learn of Cassandra's existence as an alien-human hybrid. Scully, with help from the Lone Gunmen, looks into Diana Fowley's personal history and informs Mulder that Fowley has been collecting data on alien abductees and heading to Tunisia every week, although there is no trace of her activities in FBI records. Mulder still trusts Diana, but goes to her apartment to see her.

Inside the apartment, Mulder's search for clues is interrupted by the arrival of Cigarette Smoking Man (William B. Davis). Held at gunpoint, the Cigarette Smoking Man tells Mulder that he has been betrayed by his son Jeffrey. The Cigarette Smoking Man tells Mulder that the Syndicate agreed by majority vote, against Bill Mulder's objections, to align with the alien colonists in order to delay colonization. The Syndicate were forced to give up members of their family to the colonists in exchange for the alien fetus (seen in "The Erlenmeyer Flask"). Because Bill Mulder was slow to agree, Samantha Mulder wasn't taken until after the others. Using the fetus, the Syndicate worked on creating alien-human hybrids who could survive colonization. The Cigarette Smoking Man tells Mulder that colonization will begin once Cassandra is handed over and that Mulder will be able to see his sister again, providing him with an address to the hangar where the Syndicate members will be meeting the colonists.

Jeffrey goes to Syndicate headquarters, finding only Krycek there. Krycek tells him that the Syndicate members are preparing to be given the hybrid genes—except for Spender's father, who has gone to retrieve Cassandra. Diana returns to her apartment, finding Mulder there, and the two head to the hangar at El Rico Air Force Base. Scully then contacts Mulder and the two try to stop the train car transporting Cassandra to El Rico, but fail to do so. Jeffrey arrives at the hospital, finding his mother gone. However, while at the hospital he finds Marita, who tells him to go to El Rico Air Force Base. A Syndicate surgeon attempting to procure the alien fetus is killed by one of the alien rebels, who assumes his form. Krycek finds the dead surgeon and the fetus missing, and tells Jeffrey that the rebels are now going to win. The Syndicate and their families gather at El Rico Air Force Base. Shortly after Diana Fowley arrives, a white light appears around one end of the hanger. It is revealed to be the rebels, who surround and kill the entire Syndicate except for the Cigarette Smoking Man and Diana Fowley, who escape in her car.

The next day Mulder, Scully, Walter Skinner (Mitch Pileggi) and Jeffrey report to Assistant Director Alvin Kersh (James Pickens, Jr.) on the deaths of the Syndicate and Cassandra. Jeffrey tells Kersh that Mulder and Scully could have prevented it. He recommends that they be reassigned to the X-Files and abruptly leaves the room. Heading to the X-Files office in the basement, Jeffrey finds his father, the Cigarette Smoking Man, there, who then shoots Jeffrey and leaves.