Bulletstorm Walkthrough - Act 4 - Chapter 3: Part 1
2Full Walkthrough: http://www.gamefront.com/bulletstorm-walkthrough/
Once you rescue Ishi, head through the underground tunnel to get back outside. Walk to the edge to your left and press X to grab onto the bars above you. Follow Trishka and make your way across.
After you cross the top of the waterfall, use the Dropkit just ahead. Follow Trishka and head into the building. Once you reach the huge hole in the wall, hold LT when prompted to.
Follow Trishka around the building and double tap A to slide down the slope. Wait for Ishi to kick in the wall behind you, then continue on. After you walk through the holographic clock, kill the Skulls that will be waiting for you to the left on the other side of the wall.
Full Walkthrough: http://www.gamefront.com/bulletstorm-walkthrough/