"They don't need to," declared Chet. "That's why you have to spend all your spare time learning how to catch. Even now you're not much good at it." He winked at Tony Prito, who was standing behind Jerry. "Why, I'll bet you can't catch a measly little fly--like this--look--" He took a baseball out of his pocket and threw it lightly into the air. It did not go very high and it was a ridiculously easy catch for any one. As for Jerry Gilroy, who was really a star outfielder, it was scarcely worth the effort. He had but to step back a pace and the ball was his. "Can't I?" he said, somewhat nettled by Chet's words. The ball arched through the air and descended directly toward him. He stepped back, prepared to make the easy catch. But Tony Prito had caught Chet's wink and knew what it meant, for they had carefully rehearsed the trick between them. As soon as Chet had thrown the ball, Tony knelt on his hands and knees on the grass immediately behind Jerry. For all his seeming carelessness, Chet had thrown the ball just far enough so that Jerry would have to step back to make the catch. Jerry collided with the recumbent figure behind him, he staggered, lost his balance and tumbled over Tony Prito, while the baseball thumped into the grass. The other boys, who had seen the joke from the start, laughed uproariously as Jerry picked himself up and betook himself in pursuit of the already fleeing Tony, while Chet, with an air of vast satisfaction, picked up the baseball. "I knew he couldn't catch it," he said, with all the airy disdain of a minor prophet. Just then the gong in the main hall of Bayport High began to clang, summoning the students to their classes, and the boys crowded through the wide doorway. CHAPTER IV ANOTHER VICTIM When he took his place in class that morning, Frank Hardy glanced over at the desk, two aisles away, where Callie Shaw was sitting. Callie, a brown-haired, brown-eyed miss with a quick, vivacious manner, was one of the prettiest girls attending Bayport high school. She was Frank's favorite of all the girls in the city, and each morning he glanced over at her desk and never failed to receive a bright and fleeting smile that somehow made the dusty classroom seem a trifle less drab and monotonous, and when she was not there it always seemed that the day had gotten away to a bad start. She was there this morning, but she was gazing soberly at her books and she failed to return Frank's glance with her usual smile. This was something so utterly extraordinary that Frank gazed at her, open-mouthed, for a second or so until, recollecting himself, he turned to his own books and proceeded to spend much of the time until recess in a state of helpless wonderment. Like the average boy under such circumstances, he racked his brains trying to recollect what he could have done that might have offended Callie. But there seemed to be no solution to the mystery.