The Amazing Ghost Detectives — Robert D. San Souci

Creepers! Someone's been breaking into the clubhouse in the dead of night, and the boys are determined to catch the prowler. When they realize a ghost is haunting their haunt, they call in Allison, the neighborhood ghost expert. But it's Molly the dog who turns out to be the ace ghost buster, and after an uproarious showdown the neighborhood is safe and ready for another true tale of brothers, best friends, and the extra-ordinary adventures they create.