Instructions on how to escape the 3rd class cabin in Nine Hours, Nine Persons, Nine Doors.
Seek a Way Out
To the left of the water pouring in, check the bulletin board above the sink to get the Note from Bulletin Board. Below that, get the picture of the cruise liner.
To the right of the rushing water, open the tea kettle to get a blue key. Open the stove below the tea kettle to get a screwdriver.
In your inventory, combine the screwdriver and the picture of the cruise liner, then rotate the picture to see a hint on the back.
To the left of the door with the number 5 on it, check on the mirror, then check on the red object taped to the middle of the mirror to get a red key. This triggers a story segment.
To the right of the door with the number 5 on it, check on the bottom bunk, then check on the pillow to get a Memo from Bed.
Use the blue key on the blue briefcase. Then you need to enter the correct combination.
Check the red book in the briefcase to get a stack of blue key cards. This will also unlock some menu options with helpful information, and a digital root calculator.
Check on the curtain to the left of the tea kettle to find the red briefcase. Use the red key on it. Then you need to enter the correct combination.
Get the red key cards from the red briefcase.
Use both the blue and the red cards on the card reader to the right of the door. This starts a puzzle where you have to select three cards. You need to pick the numbers that have a digital root of 5.
After you escape from the third class cabin, you will get the choice to go through the following doors: