It is bad enough Ian Barker has to spend his twelfth birthday with his younger sister, Molly, and their two annoying cousins, Vinny and Jonny. The four of them can't ever hang out without getting themselves into trouble. And Vinny and Jonny always want to play with Ian's stuff, always taking turns and breaking everything that they touch. Even Ian's new birthday presents are up for grabs. But when Ian gets Slappy from his dad, things go from bad to worse. Because when Slappy is in charge, you don't fight over him, he fights over you!