Steve, young Glaswegian just out of Barlinnie prison, comes down to London and gets a job on a building site - a melting pot of itinerant labourers from all over the country. Here he has to contend with Mick the bossy ganger trying but usually failing to control his workers and Shem, Mo and Larry and the other lads as they duck and dive through the rules and regulations of the building trade.

Stevie has other problems to contend with: the wages are low, the site teems with rats, he has nowhere to sleep and life in London isn't that easy. One day, on his way to work, Steve finds a handbag in a skip. He takes it back to its owner and meets Susan. As Stevie and Susan learn to live with the ups and downs of life in London, Riff-Raff builds a portrait, often funny, of life as it is lived in the margins.