It has something to do with the pendant that Maxi gives you after talking with him about the mysterious dreams.
Start by going to your room and sleep in the bed, then a scene will show about the weird dream. walk outside and talk with the other npcs just outside your room to trigger the quest.
Go down and talk with Maxi about it then they will give you a pendant.
Then take the elevator and go to the hotel hallway. Check the doors number plates, walk any direction you want. Find the spot to the wall between door numbers 665 and 667.
Go to that spot and click the pendant in your inventory and the secret door will reveal. Then there you will find the rest of mission for the cutscenes. Sorry if my english sucks but I hope this helps