Apparently motionless to her passengers and crew, the Interplanetary liner Hyperion bored serenely onward through space at normal acceleration. In the railed-off sanctum in one corner of the control room a bell tinkled, a smothered whirr was heard, and Captain Bradley frowned as he studied the brief message upon the tape of the recorder a message flashed to his desk from the operator's panel. He beckoned, and the second officer, whose watch it now was, read aloud: -Reports of scout patrols still negative.- -Still negative.- The officer scowled in thought. -They've already searched beyond the widest possible location of the wreckage, too. Two unexplained disappearances inside a month first the Dione, then the Rhea and not a plate nor a lifeboat recovered. Looks bad, sir. One might be an accident; two might possibly be a coincidence....- His voice died away. What might that coincidence mean? -But at three it would get to be a habit, - the captain finished the thought. "And whatever happened, happened quick.