Billy and Billie both arrive at the family home for Thanksgiving, despite Billie barely being able to contain her rage at her step-father. A family football game on the lawn leads to a drunken confrontation and an exposure of a secret.

After their mother has a barely controlled freak out about their relationship, Billy and Billie both have a strange day that tests their loyalty to each other.

Billy and Billie work contentedly together at Chisel. While Billie out for lunch, she runs into her father having a "business lunch" but his actions make Billie very suspicious. That evening, Keith sees Billy and Billie kissing in the park.

Billy and Billie try to keep their romantic relationship under wraps while visiting their parent's house over Halloween. A late night encounter with their half-brother, however, puts their private union in jeopardy.

Billie spends a long day getting advice about life and love. Billy is asked to take time off from work and he takes refuge with a sexy waitress from a local diner.

Billy makes a public declaration of his "like" for Billie and Billie interviews to become an illustrator at Chisel.

Billie bounces back by beginning a dalliance with a TV star and continues to enjoy success at work, but her world is soon turned upside down once again.

A chance run-in at a restaurant with Billie complicates Billy's work and personal relationships.

After a close call where family members walk in on them sleeping, Billy and Billie decide to put their relationship on hold. Billy bounces back quickly but Billie has a harder time of it.

Stepsiblings, Billy and Billie, reunite after many years apart and sleep together. The next morning they face the inevitable question: can they actually have a real relationship together?

In straight to camera documentary interviews, witnesses reflect on the fallout from Billy and Billie's taboo romance. The couple appears in flashbacks.