You are back in the room with the waterwheel, only this time you are a bit higher. Use the Grapple to catch the metal ring on the opposite wall and jump/ step off the ledge to hang from the cable line.

Climb up a bit and wall run to the broken ramp on the left. Go up it and kill the bats that attack.

Step on the beam and walk to the other side.

Turn slightly to the right and jump to grab the metal bar on the gate on the right hand wall.