four in the
morning
They appeared to be hunting for something , but in the meantime , they ate and soiled whatever came their way . The local cats fought heroically , but were soon killed and eaten . The rats came up from the cellar through the elevator shafts , up the steps , through the cracks in the floor , up and up till they started to run around the roof . Then , at four in the morning , they started to leave , running down the steps in close formation , seemingly panic-stricken at their own temerity and anxious only to return to their safe , dark haunts . The two scientists , in their wire observation cage , closed their note book , opened the door of the cage , and started to make a careful search of the building . It revealed nothing but the bones of cats and much spoiled food . For the next two days they worked carefully through every part of the building , hunting for something to explain the conduct of the rats .