Charlie Higson 
Sacrifice (The Enemy Book 4) 

The sickness destroyed everyone over the age of fourteen. All across London diseased adults are waiting, hungry predators with rotten flesh and ravaged minds.Small Sam and his unlikely ally, The Kid, have survived. They’re safe with Ed and his friends at the Tower of London, but Sam is desperate to find his sister. Their search for Ella means Sam and The Kid must cross the forbidden zone. And what awaits them there is more terrifying than any of the horror they’ve suffered so far . . . ** ‘Lord of the Flies with zombies’ – Rick Riordan, creator of the Percy Jackson series. ** Charlie Higson is the bestselling author of Young Bond, and creator of The Fast Show. ** Perfect for bloodthirsty fans of Darren Shan and 28 Days Later.