SOLVED: Fantasy YA where girl is looking for parents in another world [s]

[Andrea]

I know this is a long shot because I don't remember much about the book. This is a book I read around 10 years ago that was aimed at around pre-teens to teens, I think.

The main character is a girl, around 12 I think. I think her parents do some sort of dangerous job (although they might also be completely oblivious) and near the beginning of the story they disappear and she has to go into another world to find them. I forget if she knew about the other world before hand. The world is accessed through a door in a residential building, in an upper floor. I'm pretty sure it's a house in a city (and might be her house or the neighbor's). The other world has a surreal feel and is very dark. I remember being creeped out reading the book.

If anyone has any ideas I would be very grateful. Thanks!

Edit: I'm pretty sure that the door is along a long hallway with wallpaper. The wallpaper is darkly colored and might be forested, with vines. I think the MC might imagine them moving or something equally creepy-atmospheric.

I can't remember very much about the other world. I do remember that it is very murky - hard to see because it is dark.

The MC is definitely the oldest child (possibly the only child) and I think has a younger brother (at least 3 or 4 years younger).

It is possible that I am remembering a short story instead.

The story is definitely fantasy and not sci fi.

[Lobstergirl, au gratin]

Coraline?

[Andrea]

Not Coraline, unfortunately.

[Michele]

Remember anything about the cover? Any creatures or beings that the girl encountered in this other world? Any detail, no matter how small, might nudge somebody's memory.

[SparksofEmber]

Maybe try these lists? Fantasy Books Set in Two Worlds
Doors, Portals, Gates

[Mir]

Sounds a bit like A Dark Traveling. I think the MC there is a boy, but has siblings including (if I recall correctly) a girl about the age you describe.

[Andrea]

Original post updated with more information.

I didn't see anything that looked like it on those lists but I'm only partway through a thorough look through. Thanks!

It isn't A Dark Traveling, but thank you.

[Tab]

a couple more to checkout
Un Lun Dun
The Forest in the Hallway

[Andrea]

It's The Forest in the Hallway!!! Thank you so much!!