It is late June in Ballylack and school's finally out. Hannah Adger is looking forward to eight long weeks of fun and freedom, but when her classmate Ross succumbs to a violent and mysterious illness, it marks the beginning of a summer like no other.As more children fall ill, questions about what - or who - is responsible pitch the village into conflict and fearful disarray. Hannah, ever the outsider, is haunted by guilt as she remains healthy while her friends are struck down. Isolated and afraid, she prays for help. What happens next will force her to question everything she believes.