To unlock the secret ending the following condition must be met:

1. Agnes must have a positive view of Catherine to be willing to assist her

2. Obtain an emergency switch from Stockholmes's office on the 4th floor
3. Obtain a ruby name tag from the 4th floor as Agnes
4. Obtain an emerald name tag from the 3rd floor as Catherine
5. Obtain an amethyst name tag from the prison as Catherine
Check the monitor to view the camera of each prison room.
Hint: Focus on prison room A, E, F, and R.
Prison Room A:

Prison Room E:

Prison Room F:

Prison Room R:

Check the note in the same area.

Enter the 4 letter-password, it should spell out a word. The locker will open and Catherine can retrieve the Amethyst Name Tag.


6. Proceed the story as normal and escape the factory as Catherine

Good luck!