You walk up the stairs, which creak ominously under your feet, but don’t give way. There’s a corridor ahead of you, leading to several more doors, none of which match one another.

Door one is a set of lacquered wooden double-doors that wouldn’t look out of place in any fancy pants mansion, except these are clean and shiny.

Door two is painted pitch-black, with window panes that show a vast swirling constellation of stars.

Door three is sheer white with white curtains hanging from the window panes.