This film is George Lucas' directorial debut and was adapted from his very first film, which he made while at University.
Set in an highly advanced futuristic society the city in which people reside is situated beneath the Earth's surface.
This society have outlawed sex and use drugs to control the people (unfortunate enough to live here) and their 'urges'.
THX 1138 (Robert Duvall) has rebelled against this dominating regime and has stopped taking the drugs and has now got LUH 3417 (Maggie McOmie) pregnant.
Having broken the law the pair are thrown into jail where they meet up with SEN 5241 (Donald Pleasance) and the three start to plan their escape.