Writing journal: An opening sentence prompt.

I was given the prompt of the following opening sentence to be the start of todays journal writing, my story follows on from there:

“She approached the unfamiliar door and nervously took the key from her pocket. She took a deep breath, unlocked the door, paused, then opened it. To her horror she saw…”

… she was standing on the edge of a building which, in front of her, was no longer there. She staggered to grasp hold of the door frame as her head spun, adjusting to the fact that within striding distance of her position, the floor plummeted forty feet. Looking back behind her, trying to fathom how from the other side of this door she hadn’t noticed any light seeping through the gaps in the door frame, or that any breeze gave clues that what lay beyond was anything other than simply another room in this old dusty mansion, just another room she had to sort through, much like the rest....

Each room she had yet come across had been so packed full with old family records, books, precious furniture to be sold off, paintings to be boxed and catalogued, surfaces caked deep with the dust and detritus from years of unuse. There were so many rooms here and each had taken a week at least to complete, the unknown of the remaining rooms had unwittingly built up in her, a slight dread, as she anticipated more of the same. Until now. This just got complicated. This room was unfathomable. Could she call it a room? Once she had regained her equilibrium, she grasped the door which had mercifully opened towards her and closed it again. She had previously thought this bizzar that the door was hung in such a way as the room was accessed from the third floor corridor, all the other bedrooms had doors opening inwards. She stood, assessing it. Again, if she hadn’t have known what she had just seen, she wouldn’t be able to place any sign of it, this side of the door. She had been right, there had been no light shining underneath, despite the outside, vast expanse behind what was only an internal wooden door. These old manor houses did have big well built internal doors, she thought, but it shouldn’t be enough to hold back the weather and the light that lay beyond. What was more confusing was that this wasn’t the end of the corridor. She had already spent weeks processing the contents of the rooms to the right of this one and there were 3 more to the left that she was yet to approach. They had all been large bedrooms with ample space that held dressing tables and a classic couch in each, with a large ottoman at the end of each king-sized four poster bed. And yet, inexplicably, this door, which opened differently to the rest, and we now know why, seemed to take the presence of its counterparts and the interior of the rooms beyond as a personal insult, screwing up their conservative notions of four walls, a floor and correctly hung door hinges and unveiling what it, instead felt should be in its place.

Sarah moved to the chair and hallway table that sat across from the mysterious door. Run her hand through her hair as she got her senses together again. It was a few moments before she felt her legs would permit her to stand and approach the door for a second time. But stand she did, rolling up her sleeves in defiance, she grasped, once again on the door knob, retook the breath she had taken to steady herself before, and once again opened the door.