Fortunately, she had bragged to everybody about her ducky first-floor apartment in the perfectly darling three-story red-brick...When the clicking in the lock started, he jumped forward against the door. He got inside fast, closing the door behind him. A bulb in a lantern hung from the hall ceiling on a chain seemed to give a monstrously bright light. There was nobody on the stair, which went up ahead of him along the left wall. A door opened down the hall in the wall on the right. He went toward it swiftly, on tiptoe.
Source: James Thurber, The Catbird Street
I have a question. In one part,it is stated her house is a 1st-floor apartment. In the other, it seems that her house is just on the ground-floor that is on the very floor that the door to the street opens and he has not gone upstairs. Would somebody please shed light on this? What's more, What does down the hall mean? Is down a preposition here and means at the end of the hall? Or it simply says the door is somewhere on the right wall? Based on the text I have drawn a plan, is this right?