Six children, each endowed with a particular gift, feel called to Coldharbour, rubbish-filled mudflats where ships were once built. Each of them has a role to play when it comes to defending the world against the arrival of a ravenous, world-eating creature, whose oncoming roar only the children can hear.

Milo undergoes startling changes, as though some power within him is trying to break out. Thomas is not outwardly different from other children, but he has an interior Beauty — a life-enhancing force — which has a role to play in what is to come. Emily and Freda are affectionate twins who scuttle about on all fours, scaring even the gang kids on the Coldharbour rubbish tips. Their role is to know whom to look for, and to help them out. Walter is a giant of a boy, twelve feet tall and five feet wide. He is forever trusting and guarding the others. Helen can hear the thoughts of people and animals.

Each of the children has left family and home behind, except Helen who can’t bear to leave her widower father alone. Milo, turning as though diseased into a shining statue of a boy, is at the centre of their attention and causes strife among them without meaning to. Finally, his metamorphosis is complete and the six ready themselves for what is to come.

Each character is well-drawn and individual. The descriptions and interactions draw you in as you struggle with the first person narrators – Thomas and Helen – to understand the changes the children are going through and their purpose. At times the descriptions are grotesque and slightly disturbing, although not at all gratuitous: the very appearance of the twins, little girls in dresses with long hair scuttling on all fours, is enough to frighten the hardened gangs in Coldharbour. Walter is not just a large boy or even man, but twelve feet high and five feet wide. Strangest of all, though, is the transformation Milo undergoes from normal boy through apparent decay and even death until he becomes a silver guardian, a watcher against an oncoming horror.

Tim Golden is a computer programmer living in London. He is also editor of the Good-to-Read website.