What Might I Have Forgotten?
I am in the early part of the Submarine where I have found some stairs that I want to take, but when I approach them I get the message "You forgot something." (See screenshots below.) Given that I have yet to find the keys for the private room, Lower Deck - Left, Lower Deck - Right, and the Cockpit, the stairs would seem to be the obvious place to go. Hence the question posed in the discussion title. (It is possible that I need something that I failed to pick up because it required Evil alignment.)