Go up to floor 1 again.

Go here and open the secret door marked by the painting in the niche to the left. Finish with the guard to the north. Go south and west past the death chalice.

Then enter this room. Don't get surprised by the Super SS shooting plasma balls at you from behind the mirror. Bring him down. Find the captured girl in this room. Open the secret door in the fireplace. Take one cross at a time...

...and make it over to this room. Kill the two guards and...

...open this secret door. Switch quickly between a suitable weapon for the armour and the axe for the ghost. Get the bronze key in the little room past the two death chalices. Take the 1-up found in the main room if you need it.

Continue.