Take a look above on the opposite wall and you will see a metal ring. Use the Grapple to catch it...

... and jump off the ledge to hang from the cable.

Climb up a bit until you reach the spot above the support columns. Wall run and jump to grab the handhold on the left. Traverse to the left and...

... jump to grab the next handhold beneath the opening in the wall. Jump up to grab the edge of the opening and pull up. Follow the dark tunnel to the next room.

Hang from the edge of the opening and release to grab the handhold below. Traverse to the left and jump to grab the handhold in the corner. Release to grab the lower handhold.

Jump to grab the edge of the alcove on the left. Pull up and pick up the Treasure (28/30).