Smack presents a fairly realistic view of life on the streets in Bristol in the 1980s through the eyes of two runaways, Gemma and Tar. During the course of the four years the novel records, Gemma and Tar link up with drug addicts and participate in prostitution, petty thievery, and burglary in order to sustain their drug addiction. Unlike other books for young adults about drug addiction, this novel never preaches. Burgess uses the first-person perspectives of Gemma and Tar to effectively tell the story.
Other characters' voices are included to round out Gemma's and Tar's perspectives.