Complex sentence: River discovers landing patterns in Amy's garden and finds that someone has broken into the house looked through Amy's possessions, including a story book about Pandora's box, and a children's book on the history of Roman Britain.
Split into simpler sentences: River discovers landing patterns in Amy's garden and sees that someone has broken into the house. She finds in Amy's room a story book about Pandora's box and a children's book about Roman Britain.