Mulder and Scully investigate a case where people are plagued by their own doppelgangers.

When a pair of teenage girls attack one another, each believing the other to be a monster, Mulder and Scully find that their investigation could possibly lead back to their long-lost son, William.

Mulder and Scully investigate the brutal animal attack of a little boy in Connecticut, while suspecting darker forces are at play.

While investigating human organ theft, Mulder and Scully uncover a mysterious cult consumed with macabre rituals.

Mulder and Scully rush to find an on-the-run William while the Cigarette Smoking Man pushes forward with his ultimate plan.