Behind locked and barred doors, surrounded by numberless mysterious-looking instruments, sat Curlie Carson. To the right of him was a narrow window. Through that window, a dizzy depth below, lay the city. Its square, flat roofs formed a mammoth checker-board. Between the squares criss-crossed the narrow black streets. Like a white chalk-line, drawn by a careless child, the river wound its crooked way across this checker-board.