A possibly impossible request

[MisterJ]

In my custom story, quite early on I'd like to implement a seemingly never-ending hallway; that in itself isn't a problem - but what is a puzzle is that I'd like the door at the end of the hallway to lead to another room, and when a player returns through the hallway is another part of the map, a much shorter version (basically implying the never ending hallway was a figment of the imagination.)

My query is whether this could be achievable at all over a single map with scripts and such, or whether it would have to be a level-door setup?

Thanks in advance!