Biff Brewster was suddenly awake—wide awake. The gray light of dawn outlined the window of his first-floor bedroom. Something—or someone—was outside. He felt sure of it. Something had prodded him out of his deep sleep with startling suddenness.

For a moment he lay still, eyes on the window, his ears sharply tuned for the slightest sound. He knew, of course, that he might have been awakened by a stray dog, or a night-prowling cat. But he didn’t think so.

Very carefully, Biff slipped out of his bed. Bare-footed, he padded noiselessly toward the window, taking care to remain outside the dim shaft of early light coming through. He moved to one side of the window and peered out cautiously. He detected a slight movement beneath a gnarled apple tree about thirty feet away. Then suddenly, swiftly, a figure emerged from behind the protection of the tree’s drooping limbs. The figure came at a run toward the window. It was a man, small and slight of build. He was wearing blue jeans and a sweat shirt. On the shirt’s front there was an athletic letter—Biff couldn’t make it out—cut from luminous cloth, making it glow faintly in the dawn’s light.

Biff drew back, pressing his body against the wall. A moment later a white object, the size of a baseball, came hurtling into the room, tearing a hole in the screen. It fell with a dull plop on Biff’s pillow. Biff held his breath, waiting. The man was leaving the yard on the run. At the sidewalk, he slowed to a casual saunter. Apparently he did not want to risk attracting the attention of some early riser…