In **THX 1138** (1971), the film opens with a dystopian society where people live in a highly controlled underground environment. The citizens, including THX 1138 (Robert Duvall), are regulated by a totalitarian government and are required to take medication that suppresses their emotions and desires. THX 1138 works as a laborer and is married to LUH 3417 (Maggie McOmie).

LUH 3417 stops taking her medication and encourages THX 1138 to do the same, leading them to experience emotions and desire for the first time. Their newfound feelings lead to a secret romantic relationship, which is considered a violation of societal norms. This rebellion against the system puts them at risk.

THX 1138’s defiance is discovered, and he is pursued by the authorities. The film follows his desperate attempts to escape the oppressive control of the regime. He navigates through the sterile, labyrinthine corridors of the underground city, confronting the dehumanizing aspects of his world.

In his quest for freedom, THX 1138 faces numerous obstacles, including encounters with the enforcers and a relentless surveillance system. The film builds to a climax as THX 1138 escapes to the surface, only to find that the outside world is not as he had hoped, leaving him in a new and uncertain situation. The film ends with THX 1138’s escape, highlighting the themes of individuality and the struggle against an oppressive system.