Heroin addict Mark Renton stumbles through bad ideas and sobriety attempts with his unreliable friends --Sick Boy, Begbie, Spud and Tommy. He also has an underage girlfriend, Diane, along for the ride. After cleaning up and moving from Edinburgh to London, Mark finds he can't escape the life he left behind as Begbie and Sick Boy come knocking.

After 20 years abroad, Mark Renton returns to Scotland and reunites with his old friends Sick Boy, Spud and Begbie.