In the international trailer for The Girl With All the Gifts, a scene opens in a penitentiary, where the prisoners are children. After she greets head scientist Dr. Caroline Caldwell (Glenn Close), we see a young girl, Melanie (Sennia Nanua), restrained and wheeled into a room with other children – her classmates – as they welcome their teacher, Mrs. Justineau (Gemma Arterton). It’s only after Mrs. Justineau touches one of the children, causing a military serviceman to tempt the child with his arm, that we learn there is something very different about these children – they’re flesh-eaters.
As the penitentiary is overrun by the infected, a young voiceover begins to tell the story, which is mirrored by the scenes, of a beautiful woman who is attacked, but saved by a young girl – a "special girl" whom she will "never let go." After seeing Melanie is indeed "different" from her violent flesh-eating counterparts, it is decided she will be harnessed as the cure for the others, all while the fight between man and man-eater ensues.