Nate Sutter is in fifth grade and moves to a small town in California. Moving to a new place can be hard to get used to, but Nate gets along just fine, meeting his new friends Summer, Trevor, and Pigeon at school. Pigeon, of course, is a nickname, and his real name is Paul.
Eventually, the group of four children stumble upon a candy shop, the owner of which is named Belinda White. Belinda offers to give the kids candy if they help with simple tasks around the shop, like sweeping the floors. Initially, they are all too willing to give her some help, but Belinda continues to ask more and more of them. After knowing the children for a while, she tells them that she is a magician that is in search of finding treasure. If the children agree to help her find it, she will give them "magical candy".
Belinda tells the children to poison the food of Sebastian Stott, whom she claims is an evil person. This is simply too much for Pigeon and Summer, but Trevor and Nate pretend to take the job. Having common sense and good morals, they warn Stott of the evil plan, but he isn't too sure he believes them.
White doesn't find out that the boys aren't on her side until Trevor stops White from selling at her shop to prevent any more possible damage. Trevor is held hostage by White, and Nate narrowly escapes.
Later, with Trevor still in custody, Summer, Pigeon, and Nate meet John Dart, who tells them that the treasure Belinda is looking for is the Fountain of Youth. This does appear to be the most valuable treasure there is, which is why Sebastian Stott is also on the hunt for it - unbeknownst to the children.
Stott is still on their side though, or, claims to be anyway. He helps rescue Trevor, at the expense of Nate, who gets captured instead. By the end of the book, all four children are safe, but Nate was forced to get some water from the Fountain of Youth for Belinda to have.
