Two researchers at the Massachusetts Institute of Technology, Jason Nichols and Lucas Menand are having an argument while walking down a street when an elderly man approaches Lucas and warns him that he will be knocked down by a bus and killed at exactly 11:46pm.

As any sane man would, Menand tells a guard to take the man away from him as he his accusing him of harassing him so he is whisked away in the policeman's car. Moments later at 11:46pm, a bus comes along and knocks Menand down killing him instantly.

Mulder and Scully are called into the case which seems pretty simple enough as the bus driver claims that Nichols pushed Menand into the path of the bus but Nichols claims he is innocent saying that he knew that Menand was going to be killed as of the old man's prophetic visions. But when they locate the security guard who took the old man away, he is found to be frozen to death which Scully claims must have been done by an unknown chemical.

Mulder goes to interview Nichols who says they were arguing before his death because he was threatening to go public with a claim to having falsified data on a research paper. Meanwhile, the same elderly man kills a Japanese researcher named Dr. Yonechi and when the agents arrive at the crime scene they find, upon analysis, that the doctor died of an injection of an again unknown chemical. The last person now to interview seems to be Nichol's girlfriend and researcher, Lisa Ianelli and when the agents show her the chemical recovered at the crime scene, she recognizes as the same freezing agent that Nichols had been working on for years. She also tells them that the chemical has not actually been invented yet and that the doctor who was killed may not be dead.

With this information in mind, they manage to resuscitate the doctor but he quickly bursts into flames and Ianelli realizes that it was a mistake to remove him from a tub of yellowish fluid that he was already in. She now decides to confess that she was the one that falsified the data to get the research grant and Nichols is really covering for her.

Later, the police receive an anonymous tip that the elderly man and murderer is living at a hotel nearby so the agents break in and while searching through his stuff, they discover a photo showing Nichols, Lisa and Dr. Yonechi celebrating inside a cryology lab. It is then that Mulder realizes that the photo is really from the future when they had actually invented the freezing agent. He concludes that the elderly man is actually Nichols from the future coming back to try to stop this. Nichols must have tried to save Menand from getting run over and when he failed with this he killed Dr. Yonechi to try to alter the future.

Ianelli manages to find the old Nichols but he injects her with the chemical. Scully rushes to her side and remembering what happened to Yonechi, resuscitates her and puts her in the tub of yellow liquid straight away. Meanwhile, the old Nichols confronts his younger self. The old man has erased all of Nichol's files from a computer so Nichol's lunges at his old self and starts to choke him. Mulder tries to stop him but is unable to open the door to the room. Mulder yells to Nichols that Lisa is alive but instead the old man says to his younger form "It's better that we never were" and bursts into flames killing them both.

But as this is going on, Lisa is trying frantically to work on the freezing agent that is supposed to never be.....