Be careful what you wish for. Fourteen-year-old Rachel Hollingsworth ('that's Ratchet, you eejit') is sick of living in foster care. Desperate for her independence, she runs away. But unaware she's a witch, she accidentally travels back in time to the notorious Essex witch trials, along with her social worker-witch mentor Bryony and Oscar the cat. They all face execution, but their powers are failing and time is running out. They manage to escape, but to Old Istanbul. Ratchet, now a skilled fortune teller, is invited to the Palace to read the Sultan's wife's future. But the Sultana has something else in mind. She holds Ratchet's friends hostage, until she does 'one small favour'. With her friends' lives in the balance, Ratchet has to make the most difficult decisions of her life, and carry them out - all on her own.