The Spook’s Sacrifice, by Joseph Delaney (Bodley Head, £5.99).

THE scariest series in children’s fiction returns for a sixth helping.

In The Wardstone Chronicles so far, Thomas J Ward, a seventh son of a seventh son, has became the teenage apprentice of the county spook, and is learning the craft of how to combat the forces of darkness. Having battled witches and boggarts, Thomas now has to cope with the fact that the Devil has been let loose on earth and the revelation that his mother is a Lamia Witch.

The Spook’s Sacrifice sees Thomas and his master travel to Greece, his mother’s homeland, where one of the old Gods, the Ordeen, has been unleashed. Thomas and his master find themselves forging an allegiance with witches to combat this new threat. Needless to say, things don’t go according to plan.

A thrilling series that is genuinely terrifying, the Wardstone Chronicles is by far the darkest of the post-Potter children’s fiction boom. The Spook’s Sacrifice is darker yet, at some point bordering on gruesome. Recommended for those willing to risk a few nightmares.