Col lives on the Upper Decks of the juggernaut Worldshaker, a mobile city as big as a mountain. He has been chosen as next Supreme Commander - but then a girl Filthy escaped from Below appears in his cabin. 'Don't let 'em take me!' she begs.

Will he hand her over, or will he break all the rules?

Col's safe, elite world is about to fall apart.

'Worldshaker is a terrific adventure, full of sly humour, weird and wonderful characters, and plot twists I never saw coming. More, more!' Ian Irvine

'I loved Worldshaker! A claustrophobic setting of rivets, iron and steam, rustling silks and stiff collars and even stiffer manners; dark, twisting, bustling, brilliant. I was very, very glum when it came to an end.' D.M. Cornish

'I was captivated from the beginning.' Samantha, 15