Blackie stood watching the spot where the shadow had disappeared. Jimmy stared at the same spot. The dark shape surfaced again. Now it was only fifty yards away. Both boy and dog shrank back. The shape surged forward, rolled, and curved toward the dock. Jimmy yanked his feet from the water. "It's alive!" he gasped. Jimmy and Blackie, his dog, have been watching the dark shadow in the water, and Jimmy can't figure out what it could be. A submarine? A sea monster? When a couple of jeering boys ask Jimmy about the creature, he can't resist adding a few details. But how could he know that folks would get so stirred up?