Alana lives in the year 3000AD, a utopian time in which the citizens' only concern is the ramifications of The Great Disaster that befell the world in 2500AD. While participating in a time travel experiment, Alana is kidnapped by Silverthorn, a criminal from the year 2500AD, whom her tutor has accidentally brought back with her. Escaping from Silverthorn in the year 1990AD, Alana elicits the assistance of local girl Jenny to help her both stop Silverthorn and get back to the time capsule before she is stranded permanently in the past.
The Girl from Tomorrow was an early collaboration between Mark Shirrefs and John Thomson, who had previously both written for the short-lived sit-com Let the Blood Run Free. The pair became significant figures in Australian children's science-fiction and fantasy television: together, they went on to write The Girl from Tomorrow Part II: Tomorrow's End, Spellbinder, and Spellbinder II: Land of the Dragon Lord.