The Enemy Charlie Higson Wiki !exclusive!

The central premise is both terrifying and unique: Known as "the sickos" or "the grown-ups," these adults are not mindless shamblers; they retain their memories and intelligence, making them far more dangerous than traditional zombies. The story follows a band of children—from toddlers to teenagers—now forced to survive in a deserted, burning London.

There is also a companion book (2015) – a collection of short stories. the enemy charlie higson wiki