Audiobook Bob the Builder: Wendy Saves the Day. Bob, Wendy and the team have a new project – to build a treehouse for Saffi! Saffi has drawn up her own exciting designs and wants the treehouse to be the new headquarters for the Spring City Rockets. There’s a lot to do, so the team quickly get to work but the excitement proves too much for Saffi, who just can’t wait to explore her new treehouse before it’s ready.