In Van Nuys, California, two men in their early twenties named Blake and Mike (Tyson Turrou and David Faustino) sneak into a house that Blake claims was where the comedy television series The Brady Bunch was filmed. Inside, they find a perfect recreation of the house from the series; Mike, unsettled, gets worried and leaves, but Blake plods on. Blake is subsequently sent hurtling through the air and smashes into Mike's car, killing Blake.
John Doggett (Robert Patrick) and Monica Reyes (Annabeth Gish) are called in to investigate. They interview Mike, who claims that Blake died after visiting "The Brady Bunch House". The three speak to the owner, Oliver Martin (Michael Emerson), but upon entering discover that the house looks nothing like the one featured in the teaser. Doggett, feeling something is not right, checks Martin's trashcan and finds asphalt shingles; earlier, on top of Mike's car, Doggett had found a piece of a shingle. He deduces that Blake was thrown through Martin's roof. Later that night, Mike looks into Martin's house and sees the whole Brady family eating dinner. He storms into the house, only to find that the family has disappeared. Suddenly, he is confronted by Martin, who tells him to leave. Mike refuses, and is thrown through the roof, only to be embedded in the yard.
Dana Scully (Gillian Anderson) looks through various X-Files and discovers one about a young boy named Anthony Fogelman who possessed psychokinesis. She learns that Fogelman later changed his name to Oliver Martin. She meets with Dr. John Rietz (John Aylward), a parapsychologist who worked with the young Fogelman. Rietz claims that, despite being extremely lonely, Martin was not dangerous and that his power faded as he grew up. Reyes makes the connection that Fogelman changed his name to Oliver based on Cousin Oliver from The Brady Bunch. Scully notes that, in the show, Oliver was portrayed as a "jinx", and the three agents deduce that Fogelman must see himself as one, too.
Doggett and Reitz decide to talk to Fogelman. Initially, he is apprehensive and nearly sends Doggett hurtling through the roof. It is revealed that Fogelman's powers are temperamental and sometimes he cannot control them, such as the case with Mike and Blake. Reyes and Scully show up and convince him that his powers could positively impact the world. The agents take him to Washington, D.C. and his powers to Walter Skinner (Mitch Pileggi) by making him float in midair. Suddenly, however, Fogelman collapses. Scully later reports that his body is destroying itself because of his extreme power. Doggett realizes that Fogelman must stop using his powers; he notes that his power had faded earlier when Dr. Rietz was studying him as a boy. Doggett tells Rietz that his power faded because, with Rietz around, Fogelman did not feel lonely. Rietz visits Fogelman in the hospital, and the two rekindle their friendship, saving Fogelman's life. Scully laments the fact that there may not be any vindication for the X-Files, but that cases like Fogelman's might show that there is proof of "more important things."
- The title of this episode is a reference to a popular song that the Brady children sang in an episode of The Brady Bunch when they formed a band, called "It's A Sunshine Day".
- Besides the many references to The Brady Bunch in this episode, cartoon characters Daffy Duck and Wile E. Coyote are also mentioned.
- Doggett's final comment - DOGGETT: Well, here's hoping the TV stays off and he learns how to love the real world. - could easily be seen as the production's comments on its fans, especially in the period since the departure of David Duchovny.
- Gillian Anderson as Special Agent Dana Scully
- Robert Patrick as Special Agent John Doggett
- Annabeth Gish as Special Agent Monica Reyes
- Mitch Pileggi as Assistant Director Walter Skinner
- Michael Emerson as Oliver Martin
- John Aylward as Dr. John Rietz
- Tyson Turrou as Blake McCormick
- Stephen W. Bridgewater as Dr. Henry Jacocks
- David Faustino as Michael Daley
- Arlene Pileggi as Arlene
- Damon Kaylor as Orderly
- Eric Don as Young Anthony Fogelman
- Robbie Troy as "Carol Brady"
- Keith Forster as "Mike Brady"
- Marcie Lynn Ross as "Alice"
- Danielle Savre as "Marcia Brady"
- Nick Campisano as "Greg Brady"
- Stephanie M. Herrera as "Jan Brady"
- Nolan Irwin as "Peter Brady"
- Sharayah Montgomery as "Cindy Brady"
- Jack Bensinger as "Bobby Brady"