Check out the ceiling. You have to traverse forward and then left. So, jump up to grab the ceiling and start traversing forwards. As soon as you turn left, stick to the right hand side of the climbable ceiling, because the ledge Lara is heading to is on this side.

When you run out of ceiling, Lara will turn around and grab the wall behind, so keep pressing forward to make her climb up the rest of the wall. When you reach the ledge, climb to the left and drop down.