Blackfoot. Two Monarchies Sequence, #2

Bad luck is the least of their worries.Annabel has never wanted a cat. She certainly didn't want a secretive, sarcastic black cat who takes over her pillow and makes remarks that no one else ever seems to hear. Despite that, Blackfoot manages to slink into her life like a small, furry shadow. Now Annabel and her friend Peter are being over-run by cats. More and more arrive each day, turning up at the old castle ruins where Annabel and Peter spend most of their time.
And some of those cats aren't as.friendly.as Blackfoot. When someone tries to kill Annabel and a spell goes very badly wrong, they find themselves trapped in the castle ruins, which are now growing back at an alarming rate. Even more alarming is the fact that the person who tried to kill Annabel is rapidly gaining control over the magical ruins. Worst of all, Blackfoot knows more than he's telling, and what he's not telling could be enough to get them all killed.