Spook's: A New Darkness - Joseph Delaney

For years, the local Spook kept the county safe from evil. But now his time has ended, and there is only one boy who can take over - Thomas Ward, barely more than a child himself. Now he too must take on an apprentice, a girl called Jenny who is untested but willing to be trained in the dangerous life of a Spook.When girls start dying in mysterious circumstances, they soon find themselves on the path of a terrifying and deadly beast. Monstrous assassins are loose in the County, and far to the north, a new darkness is rising that threatens to engulf the whole world. Do Tom and Jenny stand a chance against the might of the Kobalos?The first terrifying tale in the Starblade Chronicles, from the bestselling author of The Spook's Apprentice