Boy-sized, boy-controlled adventure, competently told. Furthermore, there really is a bit of mystery. Howie Blake, his dog and his sister are fond of rafting around a swamp near their home. Child fashion, they surmise the presence of spies when they find some strangers camping out in the swamp. These are actually scientists trying to determine whether or not the primeval ooze has healing properties and their project becomes the children's project. Howie and company are happily wholesome; the story is active and informative. It adds up to good recreational reading for the youngest members of this age group.