Zorn's magical assult destroys the patch of green slime. There is a second curtain that looks enough like the first to convince you that it too is really Green Slime somehow morphed into a curtain.
Harrison's pyromaniac tenancies destroy the other Green Slime and reveal a concealed door as well, though you may well want to explore the clutter in this room before moving on.
"look! I found a secret door! That was more fun then finding a trap in the floor." Harrison then moves about to look at the rest of the clutter in the room.
As you search the room you find 24 locked coffers. Then Jillian discovers that there is some sort of trap that involves the whole room. It hasn't gone off yet, but could at any moment. She thinks there might be a way to disable it.
Spotting the trap the halfling thinks quickly. "Everyone, out! There's a trap in the room. Fin! Can you help me try to figure this thing out?" She quickly ushers out the others.