Make a DC 15 Charisma [or spellcasting ability] (Intimidation) check (whichever is higher).
If you succeed, click the spoiler box below:
You hear a combination of startled yelps and cries, coming from behind the stalagmites and the pile of supplies.
Close this tab and go to the second grey spoiler box under Area 8 in the Play It Solo article. Pick option 1 and resolve the encounter as described there.
Close this tab when done.