> But if only the holder of the key is dead, and you have other guys left alive, you can transfer the key to someone who's still alive and don't have to get another one.

I wonder if the problem is that the key holder is dead in Kaliti and the others are on the *wrong* side of the locked door in level 4.

If that's the case, the swiftest solution, I think, is just to go get another key, as others have stated.

If you want to take a risky approach, though, go back to Perinn, then jump to Kaliti. Create some disposable characters to accompany the dead key-holder out on a quest. Then have them leave Kaliti. It'll be rough, and you'll probably have to run from every fight (so spend all your character-creating points on agility for the throw-away characters), but if you can manage to outrun enough monsters to make it to the elevator to level 1, you should be able to rejoin the other members of your party in Perinn with the key.