The X-Files: I Want to Believe movie is the second feature film based on Carter's TV series The X-Files. Fox Mulder and Dana Scully both worked at the FBI as partners, a bond between them that led to their becoming lovers. But now they're out of the FBI and have gone their separate ways.
Scully works as a staff physician at a Catholic hospital. Her focus these days is on a young boy with an incurable brain disease. Administration wants to give up on him. Scully, who feels a special bond with the boy, does not. Meanwhile, Mulder's focus is on clipping newspaper articles about the paranormal and throwing pencils into his ceiling.
Scully and Mulder are brought together again when a special case requires Mulder's expertise, and Scully is prevailed upon to find him. The case involves a pedophile priest who claims he is having psychic visions regarding the whereabouts of a missing FBI agent.