Exit at the dock and kill some rats. Go around the building to the left, killing the guard and his rats before flipping the switch. Another guard arrive so kill him too, taking the medkits from both your victims. Enter the now open front door and kill the guard on the balcony and his friend who appears on the ground floor. Grab the shells from your second kill then shoot out the window and kill the Dobermans who jump through when you get too close. Go to the back of the courtyard and take the medkit, flares and ammo.
Now you need to proceed down the heavily guarded hallway. Several statues will begin hacking at you with huge blades when you get too close. Keep to the right and time your short running bursts so you pass by when their blades are in the upright position. Don't overshoot and run into the next blade. When you get to the dark end of the passage, light a flare to reveal a switch which opens a door back out by the canal.
Run past the guards in a single continuous run this time. They will swing but they will be too late. Back out in the big room find the sloped wooden box. Stand with your back to the slope then jump back and then forward and grab the ledge and pull up. Walk around to the left and pull the block then drop down to the floor. Get below the ledge to the left of the block you just pulled and jump and pull up. You can now turn and do a running leap to the opposite balcony where you killed that first henchman. Take his ammo then move to the textured wall and climb on and across to the window.
Climb out onto the ledge and turn to the right and dispatch the gunman on the balcony across from you. Now you can turn and do a running jump off the end of the balcony over to an awning. You'll start sliding backward so grab as you fall then shimmy to the left and pull up and do a backflip to a ledge across the canal. Turn left and do another running jump, grab and pull up maneuver. You should now be standing on a rather small ledge. Turn and do an angled jump to the awning across the canal. You can stand on this awning so turn and face that open door and do a standing jump and press the grab while in midair so you enter the door instead of hitting the wall above it.
A pair of Dobermans should charge you when you land so take them out before they even get close. Make sure you don't back up or backflip out of the door into the canal or you will be doing that last paragraph all over again. Head upstair and take out the first of many attacking gunmen.
Enter the room where the first henchman came from and look in the left corner for a switch hidden in the wall. Flip it to open a door in the previous room which leads to that outside balcony where you killed that one guy. He dropped some shells and Secret #1; the Stone Dragon when he died. After you collect all of this, return to the room with the switch and shoot out the window.
A guard patrols the landing outside this window. You can probably kill him as he passes or you can climb out and do the deed face-to-face. Continue down the landing and shoot out the next window and climb in. The door opens and a guy with a bat enters along with his dog and another guy shows up behind you on the ledge. These guys are pretty slow so as long as you keep moving and firing you should be okay. The dog is faster to take him out first if possible. Do a lot of flipping and use the larger room on the other side of those doors if you need space to maneuver. You can even retreat back to the stairs if necessary. When everyone is dead, return to the last room and push the back of the fireplace twice to access a concealed passage.
Kill the rat after you climb up then proceed to the slope. Blades start slicing at you as you approach so stand back and jump out and turn to the right and drop into the water. Climb out to the safety of the wooden ledge in the corner to survey the next deadly trap.
You need to make a quick series of jumps and the flames are on a timer. They will go out when you jump off the ledge you are standing on, so when ready, get your back to the wall and start running. Jump from the edge and land on the next platform. Do two STANDING jump for the next two ledges to arrive at the other end of this trap. If you miss a ledge or catch on fire you will land (or can jump) in the water and try again.
The door open as you approach and a gunman and his dogs attack. Kill them all then jump to the slope box and jump and grab and pull up onto the lowest chandelier. Do a running jump to the right to grab the ledge. Pull up and flip the switch to open a door behind the fire in the fireplace. Jump back to the chandelier then turn and jump to the next highest chandelier. Do another running jump to the ledge on the right to flip another switch which opens a painting on the wall which conceals the Library Key.
Return to the chandelier then turn right and jump to the next highest light and finally to the ledge above. Kill the approaching rats then continue in their direction and jump and grab and shimmy to the right until you can pull up. You should now be on the highest rafter so run and jump to the wood floor by some bricks. Kill the henchman behind the bricks and take the medkit. Be careful not to fall off as any fall from this height is instant death.
Climb on the bricks and head left and jump to reach another switch. Flip it to adjust the chandelier height so you can access the Library Key. Jump back to the bricks then go down to the chandelier and jump until you reach the light next to the Library Key. Do a running jump to grab and pull up and get the key then repeat to get back out on the chandelier. Jump all the chandeliers until you are on the other side then do a running jump and grab to the ledge. You won't grab but you will land on the ledge and this saves you from having to return to that last switch to adjust the chandelier heights.
Exit to the window sill and go right. You should see the fire below, so hang and drop down to land in the water and not the fire. You should now be outside the Library door. Flip the underwater switch and swim through the door that opens as a result. Head to the right and surface. You should see a gap in the floor to your left. It's dark down there so light a flare and head into the opening. This turns into a maze rather quickly so follow these directions.
As you swim into the hole turn to the right and go around the corner. Swim into the large opening then go through the smaller opening near the top of the wall. Turn right after entering the smaller passage then find the small opening to the lower-bottom-left of the wall. Enter and immediately turn left to find some grenades before continuing back to the right to find Secret #2; the Gold Dragon. Flip the nearby switch then head straight up to the newly opened door where you can finally take a breath. Do NOT climb out here or you will burn to death. Instead, retrace your path through the maze back to the library door.
Enter the Library and kill the gunman across the room. Go through the large doors and climb up the bookcase on the left. You can kill a pair of rats from the small area above before jumping over to flip the switch which opens another guarded doorway.
After you kill this guard, go through the door and climb the books on the left. Jump towards the window then turn left and climb up. Shoot the window then jump to the sill. Turn and exit the window backwards so you slide down the awning. Grab the end the pull up so you backflip to a ledge behind you. Run and jump to the roof across from your new position, then turn left and jump to the TOP of the brick wall.
This next sequence is extremely difficult (at least it was for me) so SAVE frequently.
While standing ON the wall, walk to the end to the top of the slope. Turn so you are facing the building across the canal and do a running jump to grab the lowest section of the roof. Pull yourself up and head for the smoke stack. Stand a few steps back from the edge of the roof and jump toward the ledge. Grab on and shimmy left until you can pull up. Go behind the wall to find a pool of water and a pair of Uzi's.
Drop down next to the shack and kill the henchman, taking the ammo he leaves behind. Take the Detonator Key from the table then step towards the door and it will automatically open. Kill the gunman on the other side, taking evasive action if necessary. Take his medkit before returning to the main room of the Library. There is a switch on the wall so flip it to open the door. Enter and kill 2 more gunmen who approach from the left. Relieve them of their shells and Uzi ammo before continuing.
Don't use the key in the Detonator box just yet. Instead, climb to the top of the brick wall and go to the left end of the wall. Pull up twice so that you are now standing on the sloped roof. Shoot out the glass and take Secret #3; the Jade Dragon from the table. Jump into the water and swim over to the low brick wall with the Detonator Box. Use the key to blow up the building, then kill that gunman that is above and behind you.
Climb onto the brick wall to gain access to the demolished building. Begin the long ascent to the top of the rubble. After much jumping, grabbing and pulling up, you will reach the top and can take the path which leads to a dark hall and the end of this level.