There seems to be some kind of a bat creature caught in the net. Help him by pulling the rope that hangs from the net. And so you have found our furry friend. But unfortunately it doesn't help much. Grab a sharp stone fragment from the floor and slide thru the upper tunnel.
Friends can be very useful at the tight places.
Use stunner to dispose of any bothering flesheaters. Talk to the bat creature and touch that big pillar. Get that shiny box and leave at once. Climb out and walk to the pillar with secret door in it. There is a big rock quite near to that pillar.