Shades Children by Garth Nix.
"most (children) don't have the guts to slice open their own wrist, to reach in and pull the capsule out from where it nestles between veins and bone. "
One day, now long in the past, all humans over the age of 14 disappear, never to return......
In their place, arrive the tyrant overlords and several freakish hoards of creatures from an alternate dimension. All the children are rounded up and placed in dormitories, there to be trained and raised.
At the dawn of their fourteenth year, upon their sad birthday they are sent to the meat factory where their muscles, brains and bones are transformed into yet more creatures for the overlords to use in their senseless bloody battles.
Gold-eyes a boy nearing his sad birthday manages to obtain a razor. After a grisly and painful removal of his tracking capsule he escapes in a desperate ploy to extend his life. He finds ruined buildings, constant danger from the creature and finally he finds Shade.
Shade, a cold cruel and calculating computer program, once a university professor now the last hope of the escapees. However the food he provides is not for free, he requires information on the overlords and such information is costing lives at an inhuman rate.
Shade's children is dark. Dark in the story it tells, dark in its ruined streets and dark in its disfigured characters. It is refreshing to me to read such a story, one without cute little bunnies and fairytale characters, Shades Children is real in its darkness and original in its ideas.
A decent book I give it three out of five.
