Ruby and Garnet are identical twins who once lived with their Dad Richard and Gran in Birmingham. Their mother Opal died a few years earlier. They are happy together, but then Dad gets a new girlfriend, Rose. The twins and Gran hate her.
When a layoff shakes up the family, things take a turn for the worse. He moves the family away from their familiar home and sends Gran to a Senior Citizens’ Home, while the three girls are taken to the countryside to open a bookshop. The venture falters, and the shop’s struggles leave the family feeling pressed and uncertain about their future. The twins find themselves navigating a new school environment, where they quickly make enemies—Jeremy, a larger boy who they nickname “Blob,” and his gang. Garnet also befriends a girl named Judy, offering a small pocket of companionship in a new place.
Because they despise their new life, the sisters push boundaries at school in a bid to be expelled and return to Birmingham, only to regret it after the fact. They apologize to their Dad with a simple, homemade gesture—biscuits—and momentarily soften the tension that has built up at home.
A turning point arrives when Ruby discovers a newspaper ad for an audition for a television adaptation of the novel The Terrible Tempest Twins. Garnet is hesitant, but Ruby pushes ahead, asking their Dad about the opportunity. In a rash moment, Ruby steals money from Rose and urges Garnet to sell Gran’s doll for £20 to fund their trip to Birmingham for the audition.
The casting process moves quickly. The casting director, Jacqueline Wilson, is impressed with the sisters, though their father retrieves them and brings them back home. That night, Ruby makes a brief televised appearance, waving to the camera as the filming location—Marnock Heights, a boarding school—appears on the screen. To pursue Garnet’s future, Ruby writes to the headteacher and receives a brochure back. They learn that the scholarship required to cover the £10,000 cost is not guaranteed; only one girl can win it. The girls endure the entrance exam, and the competition for the scholarship becomes a personal battle between them. Ruby’s confidence is high, but Garnet earns the place, triggering a harmful jealousy in Ruby, who copies her to become more like her sister and even goes so far as to cut Garnet’s pigtails during a moment of frustration.
Tensions rise, but the siblings eventually begin to heal. On the day Garnet is about to start at Marnock Heights, Ruby’s anger subsides, and she apologizes. The pair slowly rebuild their bond, with Garnet even getting a new mobile phone to stay connected, and life in their new arrangement starts to feel more stable and hopeful.
In the end, the film closes on a hopeful, united note. The final moment is underscored by a defining line and a memorable song choice that plays over the closing credits.
> We’ll always be Ruby and Garnet, for ever and ever and ever.
The closing credits feature the classic duet "It Takes Two" by Marvin Gaye and Kim Weston, weaving a sense of enduring partnership into the last image of the twins.
