I have found it. This company makes bookshelves to fit in your doorway and make a secret room.
Hidden house (secretly: Operation Hobbit Hole)
A Hidden Room
Hidden room would be so cool!
Hidden lock for doors drawers uses magnetic key.
Secret doors- genius!
Bookshelf slides out to reveal more storage tucked into the slanted roof area. Dachausbau als Wohnraum » Häfele Functionality World
Hidden Bookcase Storage - 15 Secret Hiding Places That Will Fool Even the Smartest Burglar