Alright I have these in my mind
Lil Chum and Lil Isabella are Siblings (Similar to Sprig and Polly)
One of the 4 teens found a Golden door that was attached to a tree. The door has Logos that looks like a Cheese, Dog bone, Dead fish and two Snake fangs crossing as a X (I can't come up with anything)
the door is covered in Leaves.
As you were wondering why they are at the forest at night.
Well they Snuck out.
Once they open the door.
What's behind the door was a Portal
All of them got sucked in by the portal.
Everything went black
The reason why I called this story The Mouse world is because the Main character thought he was in the the World where mouses Existed but he doesn't know that the world has Cats, Dogs and Snakes too.
Annie Catsoy is based off of Anne Boonchuy
Since she has Domino as her Pet so it kinda make sense