Hoot and Bentley know the most important rule of time travel: Don't mess with history--especially your own history! Still, a quick trip can be hard to resist when you really, really need to ask your future self an important question--or get your grandpa the coolest birthday gift ever. But after a visit to the roaring (or were they mooing?) twenties, a groovy trip to the disco era, and an adventure in the world of Sherlock Holmes, our favorite partners-in-time have to face facts: Mistakes they made millennia ago have followed them home!