Scully is tricked by the Lone Gunmen into accompanying them to Las Vegas, where they make a startling discovery.

The episode begins with a "Previously on the X-Files" segment, showing the Lone Gunmen's previous encounter with Suzanne Modeski, then shows an opening narration by Byers in which he says he dreams of living the perfect life but the dream always ends and he loses it all. In his dream, Suzanne is his wife.

The Lone Gunmen are at the hotel hosting "Def-Con '99" in Los Vegas, a convention of black ops technology and trying to discover details of secret technology, although they are not allowed in to the conference itself. In a complicated ruse, Byers is in a private poker game, pretending to be a defence contractor, but another player, Grant Ellis entraps him with fake jargon, and Byers is kicked out, losing $3,000 in the process. The Gunmen return to their room. Two other geeks come to their door, Jimmy and Timmy, and invite them to go to supper. In a private moment, it becomes clear that Byers pushes for the Gunmen to attend such conventions because he is looking for Suzanne - they first met her at a convention in Baltimore. On the way to supper, Byers sees Suzanne in the casino, but cannot catch up with her.

Mulder calls Scully in the middle of the night, telling her that the Gunmen have found something big and she has to come to Los Vegas, but it is the Gunmen using a computer to fake Mulder's voice. Later, getting ice, Byers sees Suzanne again. A man enters her hotel room and she kisses him. The Gunmen hack into the hotel computer and learn that the room belongs to Grant Ellis, who they learn is an employee of the Advanced Weapons Research facility, where Suzanne worked ten years earlier. Byers urgently wants to get into the closed room where the actual Def-Con seminar is taking place. Jimmy knows how - he crawls through an air duct. He sees Suzanne in the room, and is surprised to see his friend, Timmy - Timothy Landau - also in the seminar. Jimmy is caught and injected with something. A short time later he jumps in front of a bus, killing himself. Meanwhile, Scully has just arrived and she wonders why she can't reach Mulder by phone.

Frohike, dressed as a maintenance worker, gets into Suzanne's room to plant a video recorder in the room, but he finds a recorder already there, in an air duct. Suzanne returns and Frohike hides in the bathroom. Then Byers comes to the door. Suzanne recognises him but denies she has been brainwashed. Yes, she was kidnapped ten years earlier, but "things got better." While they talk, Frohike escapes through another air duct. At the morgue, Scully begins an autopsy of Jimmy. Langly is there, but has to leave the room because he gets sick. While he is retching, Landau finds Scully and injects her. Langly finds her on the floor, groggy and thinks she is jetlagged. She acts goofy, but says she found nothing in the autopsy.

The Gunmen later watch the tape from the Suzanne's room. She comes to their room, and wants to explain to Byers, asking the other two to leave. "THEY" took her and did terrible things, but Ellis saved her. "I wanted it to be you, John." She didn't trust Ellis at first, but then realised he was working against them from within. They had planned to go public on the last day of this convention, expose THEM and escape. In the casino, Landau, still posing as a geek, invites Langly to a Dungeons and Dragons game, but when they get to the room, Langly is injected. Frohike, meanwhile, finds a giddy Scully, surrounded by men. (Fans will notice that Morris Fletcher is one of them). Scully is acting like a bimbo, but Frohike grabs her and takes her back to the Gunmen's room. Suzanne recognises the effects of a drug she developed, "AE," which impedes higher brain functions and makes the victim subject to suggestion. She gives Scully an antidote. Langly is also back in the room.

Later, Langly returns to Landau's room, with his hair short. He is programmed to get into the seminar and is given a gun. At a conference break, Langly approached Suzanne and shoots her in the chest, but it is a setup. Suzanne had discovered that Langly was injected, and also given him the antidote. Frohike and Byers arrive, dressed as ambulance technicians, and take Suzanne away. Scully takes Ellis into custody and takes him to Suzanne's room, where he realises she was not hurt. She is left alone with Ellis and he says he had to trick her to save his own life. Landau enters and shoots Ellis, then takes Suzanne to the Gunmen's room. After a scuffle, Landau is injected by Byers, and pacified. He is eventually charged with murder. Scully finally reaches Mulder by phone, and realised he knows nothing about what is going on. Suzanne is legally dead and Byers provides her a new ID. She asks him to come with her, but he says she will be safer without him. She promises him "some day..." and gives him the wedding ring she had bought for Ellis.