Abi and her two step-brothers, Max and Louis, find that strange things happen when they are alone in their eerie, ivy-covered new house. Abi, reading alone, finds herself tumbling deep into books, while Louis summons a startling guest through his bedroom window. Even Max has started to see shapes in the shadows…

Their busy parents see none of it – but Louis’ secret visitor is growing too alarming to keep secret, and he finds he cannot manage without Max and Abi’s help.

Can they find out where the mysterious creature has come from – and how to get it back there?