midnight
`` Careful , now , '' warned Garry . `` Whistle at the first sign of trouble , no matter how slight it is . '' Phil and Dick sprang up the stairs , noiselessly , yet speedily . There was not a sign of noise , all was as quiet as a cemetery at midnight . Left alone , Garry went along the hall , stopping at each door and listening intently . He was unrewarded until he came to the end door . Here he thought he heard a sound of scuffling and squealing .