Kour, I little confused I am 
You said that watcher found dog (singular), yet you marked two on the map (though this is consistent with what the guards were saying).
Under the backstage means that the area around the T-like things is a backstage.
Does it mean there is a cellar or that the stage is like one meter tall and there is something below.
also where are we (where's the bar) and how the rooms to the east (near the main entrance) are accessed?
and how many other people are around - is it crowdy, or there are just we and the guards?
Sorry, the making of this was stretched too long, so i myself am a bit in over my head, in adjusting it.
My mistake in English, There are 2 dog-like creatures inside the club, and a few stray dogs outside

The area that is blanked out to the right of the t-like things on witch girls dance is the backstage, at least girls come and go trough the 2 doors there.
Also doors are the white rectangle spaces in the walls. there is no basement, the dogs are around, not under, meaning you do not know the exact layout of the backstage.
The two round-things top and bottom of the map are the Bars. there are 2 drinks can be consumed at the bar or taken to the seating at the T shaped stages
At the moments the map only shows the rooms you have been in, the whole second floor is blanked out as well as many rooms in the first floor.

You can start investigating

2 stories, with a roof access.
Simple perception test should let you see the door markings, toilets stairs and such

Waiting to see what you all do
