six o'clock
`` Would she take the key and leave the door open ? '' `` Why -- no ; that _ is _ strange , Mary Louise . '' `` The detective did n't inquire at the office whether the night clerk had seen Alora pass through and go out . But _ I _ inquired , Gran ` pa , and the night clerk goes off duty at six o'clock , when the relief clerk comes on , but neither saw any girl at all leave the office . No one was in the hotel lobby , at that hour . '' `` That is strange , too ! How could Alora get out , otherwise ? ''