The Spook's Nightmare by Joseph Delaney

The Wardstone Chronicles series. Random House, 2010. ISBN: 978 0370329819.
(Ages: 10 to 14)
In the eighth book in the Spook's Apprentice series, Tom and Alice return from Greece to find the County under siege and the Spook's home burnt to the ground, including his library containing all the information related to his duties as a Spook. Like many others from the County, Tom and Alice flee to seek refuge in the neighbouring island of Mona. Unfortunately for Tom and Alice, Mona is under the control of a malicious Shaman. Soon after arriving in Mona, Alice is accused of being a witch and Tom of being in league with a witch. As a result, they are both arrested and taken to the infamous Greeba Keep where Alice is tested to be a witch by rolling her down a hill in barrel full of deadly spikes. Surviving this, Alice and Tom aim to plan their escape by fighting the famous transforming buggane monster and working reluctantly with Alice's mother, the untrustworthy witch Bony Lizzie. Tom's loyal canine companions Claw, Blood and Bone are turned against him and each other for the brutal pleasure and entertainment of the Shaman. There is plenty of action in this book to keep readers entertained, and Alice and Tom further explore their indecisive friendship with each other tainted by Alice's relationship with her mother.
Adam Fitzgerald