A two-part adaptation of the Iain Banks novel of the same name, "Stonemouth" is a rite of passage tale set in the fictional Aberdeenshire village of Stonemouth which follows Stewart Gilmour, who returns to the village for his best friend’s funeral. Run out of town a year earlier by his girlfriend’s family, Stewart is forced to face up to his own past whilst uncovering the sinister truth behind his friend’s apparent suicide.
Stewart Gilmour arrives home in Stonemouth after two years in exile. Sad circumstances bring him back: his best friend has died, apparently at his own hands. Convinced it can't be suicide, Stewart resolves to find out what really happened, which means he must face the girl he left behind.