I hope you mean the cave that have fire skeleton in the middle and then you can enter a room that after the first door there is an oil barrel going boom when you cross the door+ Fire balls all over the place that can be stopped with the lever in the upper corner, and there is a door with more pressure plates.
if so!
as far as I remember there is a key in the room
(and I think there is another key in the corridor after the door)
print screen If you get into trouble I will try to help you