Having done so, go back down the stairs and go up to the second floor on the other side of the room. Right at the end, behind the last screen, you will find a medikit; you then need to kill the sniper, break the railing and gather enough momentum to be able to reach the head of the dragon from where you can exit the level.
Making use of the beams, move along until you are directly above a cabin. Drop down onto this cabin and operate the lever inside (the cabin begins to move). With the transformation now finished, allow yourself to fall carefully (some packing cases cushion your fall). Observe the comings and goings of a robot and take the door through which he enters and exits.
Enter the building. Try to spot an opening in the ceiling above the presses; it's the secret passage which will allow you to gain access to a cistern full of water (for transformation into Hyde). Once you've made the change, take the staircase and go down to the basement. Pick up a case and throw it at the grill which is blocking access to the lift. Now you can use the lift.
Make your way to the quayside, avoiding the sniper fire. Leap onto the bridge of the ship, turn and climb on top of the cargo, jump onto the wheelhouse and then make another leap towards the window (which you go smashing through) to confront Mr Yang. Once you have overcome Mr Yang, pick up the medikit and activate the lever on the control panel (it opens the aquarium). Enter the aquarium and break it from the inside before you become short of air. Exit the aquarium, whereupon Hyde turns back into Jekyll, and you can now take hold of the first part of the 'key'.
Go up to the higher level, while watching out for snipers (who are crisscrossing your route). Leave via the large door.