Let Lara slide down a bit and jump forward to grab the handhold on the square pillar ahead before you fall into the chasm. Jump up to grab the egde of the pillar and pull up.

The camera shows where you need to go, so hang from the left edge of the pillar and traverse left if necessary. Release to grab the lower handhold and...

... release once more to grab the horizontal pole below.

Release to land on top of the pillar below. You will not be able to see Lara, because she is inside the V-shaped rock. If you move on the spot, you will be able to see her shadow.

Jump up to grab the handhold on the next pillar and traverse to the right around the two corners.

When you reach the broken part of the handhold, release to land on the beam below. Turn around and walk to the other side.

This beam does not reach the next pillar, so jump the gap to grab the narrow ledge there.

Traverse to the right around the three corners and pull up on the wider ledge.

There is a beam exactly below, but do not go there. Instead, perform the Chimney Jump to grab the edge of the safe walkway above. Then pull up.