YA book about a girl and a tree house?

[Brandie]

It is a regular young adult book. I can't think of any sub themes. All I can remember is it is about a girl who befriends another girl and they are messing around in the abandoned part of town and there was a tree house that either her father built or she was building it during the story. The other girl disappeared or moved away. The two girls went rummaging through a movie theater or something. I think I read it in 2011 to 2013 I can't fully remember the year.

[Lobstergirl, au gratin]

Brandie, are you still looking for this or did you find it?

[Lobstergirl, au gratin]

No response. Moving to Abandoned.