A few minutes before midday, a lanky, slow-moving maintenance worker named Billyboi Noble lowered himself into a shallow pit beneath the shaft of number four elevator. His business there was routine cleaning and inspection, which he had already performed this morning on elevators numbers one, two, and three. It was a procedure for which it was not considered necessary to stop the elevators and, as Billyboi worked, he could see the car of number four - alternately climbing and descending high above.