In the near future, humanity has been ravaged by a mysterious fungal disease (a mutation of Ophiocordyceps unilateralis). The afflicted are robbed of all free will and turned into fast, mindless flesh-eaters, referred to as ‘hungries’. Humankind’s only hope is a small group of hybrid, second generation children who crave living flesh but retain the ability to think and learn. The children go to “school” at an army base in the Home Counties, where they are experimented on by Dr. Caroline Caldwell. Helen Justineau is responsible for educating and studying the children. The children are prisoners, but humanized by Helen to the dismay of Sgt. Eddie Parks. Helen treats the children fairly, growing particularly close to a polite, exceptional girl named Melanie. After Melanie reads her own story to Helen, Helen is overcome with emotion and strokes the girl’s head. Parks bursts in and rebukes Helen; he rubs off a “masking gel” on his arm, and then holds the area near a child, evoking a violent, animalistic response which then spreads to the other children
As punishment, that evening Parks leaves Melanie restrained in her wheelchair. Helen visits Melanie in her cell and tries to release her, but Melanie starts snapping and trying to bite Helen. Melanie struggles to restrain herself to impress Helen, but is unable so Helen flees the cell. She drops her blocker lotion by the door, which is discovered later by Dr. Caldwell.