Swamp Mysteries — Elizabeth Singer Hunt

Charley, Oscar, Robbie and Jules are ordinary 12-year-old kids. That is, until they uncover the long-lost treasure map of the notorious pirate, Jean Lafitte. Soon, a couple of greedy alligator hunters are on their tails, as are the ghouls from the nearby swamps who will do anything to protect the treasure. If Charley, Oscar, Robbie and Jules are going to make it out alive, they're going to need more than luck. They're going to need the help of the ghostly inhabitants of Plantation View, Louisiana.