The Explorers: The Door in the Alley
This is one of those stories that starts with a pig in a teeny hat. It's not the one you're thinking about. (This story is way better than that one.) This pig-in-a-teeny-hat story starts when a very uninquisitive boy stumbles upon an alley he's never seen before. And down that alley, a very mysterious door. After that there is danger, adventure, missing persons, hired thugs, a hidden box, a lost map, multiple explorers, and a girl looking for help that only uninquisitive boys can offer.