Follow Bentley's advice and slam the fire grate shut, breaking a clue bottle in the process. Head down the hallway and take out the hammer enemy, then jump to a hanging walkway and cross over to the platform rising up out of the water. Before jumping up to the next walkway, break the clue bottle hanging down from it. Keep going past a welder and hammer enemy jumping from platform to platform until you reach the big wooden column. Use to circle around it, then climb the rope on the other side. Circle around the upper part of the platform, past where you can get off, all the way to the clue bottle. Go back and jump over to the next hanging walkway, which leads to a rotating platform. Go down the pipe off the other side and take out the hanging bottle and then the one bouncing on the wheel handle off to the left.
Bust open the grate at the end of the rotating pipe and head inside and take out the welder. The next section has a bunch of fire grates with their doors up and bottles all over the place. You can't come back up here, so if you don't get all the bottles on the way down, you'll have to go through the level again to pick up the ones you miss. Jumping on a grate will let the bottle on top of it fall down where you can break it when you get to the bottom, but you'll need to hit the hanging ones in air before moving on to the next set of grates. Jump from one grate to the next on the same level, breaking the hanging bottle between them, then move on to the next lower level and repeat. If you keep going after the lowest set of grates, you can land on the pipes and pick up an extra life. At the bottom, grab any bottles that dropped down, then continue down the hallway and bust open the grate at the end.
Here you'll need to avoid the spinning fan blades. Just run through after one passes, then stop and wait for the next one. At the end is a welder and a rope you can climb up to the next level. After taking out the hammer enemy up top, jump onto the pipe and crawl along to the first fan blades. There are gaps in the pipe showing you where the fan blades pass, so stop before crossing them and wait for a fan blade first. Halfway across you'll need to jump to the next pipe and continue through more fan blades to the end platform. From there use the ring to swing over to the next tunnel.
Past the hammer enemy, you'll see more grates and bottles. This section is just like the fire grates you jumped down before, except with laser security. The alternate at each level, so you'll want to start when the top one is clear and go down like before, jumping on each grate and hitting the hanging clue bottle in between before going down a level. At the last level, make sure to jump out to the pipes to collect the bottle there. It's also easy to just drop on top of the hammer enemy below from the pipes. At the bottom, grab any bottles that fell down and continue down the hallway where you can bust out another grate.
Take out the hammer enemy, then move onto the rotating pipe behind him and jump onto the spinning wheel on the left to hit two more hanging bottles. Keep going past the welder and jump down to the left to grab another bottle on some machinery. From there take the pipe up to the next level and cross the lava to the hammer enemy. Take him out and break the small safe for two more bottles. Head back around to the other side of the big spinning wheel in the center of the area and jump on the pump platform. Jump backwards and catch the ring behind you, then swing back forward onto the machinery behind the pump platform to go up to the taller platform. Look off the side of the platform and you'll see the last bottle hanging over some quickly spinning pipes. Jump over and break the bottle, then drop down behind the wheel to the safe where you'll can enter the code and pick up some more pages to the Thievius Raccoonus.
Take the pump platform back up to the main platform and grab onto the hook up there to slide over to the end of the room. Jump off and head down the tunnel, closing the fire grates as you go. In the next room, just double-jump over to the key and break its case to finish the stage.