Charlie Bone and the Blue Boa (Children of the Red King) Book

Charlie Bone and the Blue Boa is the third book in Jenny Nimmo's Charlie Bone series.

There is a rumour going round that a ghost is living in the attic of Bloor Academy. Charlie and his friends decide to investigate when they are stuck in the Academy one weekend due to detention. They discover that there is no ghost but there is an invisible boy. The boy had irritated the Bloors and they had then used him in an experiment to find out whether the mythical Blue Boa could actually turn people invisible. Charlie decides that he must help the invisible boy and also the Blue Boa.

The blue boa actually turns out to be a really interesting character here. It was originally the protector of the Red King since people were frightened of it even though the snake was actually very friendly with its master and other friends. One day the Red King's son Borlath caught the Blue Boa and tortured it until it became a dangerous killing machine. But that is not the end of the story as Charlie takes pity on the Blue Boa and tries to help it at the same time as he is trying to stop Olly from being invisible.