There are many alternative ways in which you can achieve your objectives. The purpose of this walkthrough is only to provide a means by which you can find loot, answer questions etc. I have broken it up into sections, so that you can avoid spoilers for areas that you wish to discover for yourself. 
LOOT LIST

STREET	CATACOMBS 	TOMBS	
Seminary 75	Cat arches 200	Hytheance 100, 225	
Library 50	Tower 45	Rembrath 75, 100, 50, 100	
Bell Ringer 120, 50		Larkhale 350	
Luthor 50	 	 	
Grotto 200	 	 	
TOTAL 545	TOTAL 245	TOTAL 1000	
GRAND TOTAL 1790 
LOOT REQUIREMENTS

Novice	Catpurse	Master	
850	1200	1500	
About Town 1 
Pembersham St 
NOTE: By avoiding knocking out guards now, you may inadvertently make your survival easier in a later part of the mission. 
Stay in the shadows and peer around the corner to carefully watch the patrol paths of the guards. Wait until the female guard has turned around and either blackjack her and quickly dump her unconscious body next to the generator before the other guard sees you, or just hide next to the generator and wait for the guards to pass you on their return patrol. When they have passed you, run up to the nearest door and pick it quickly. Inside the Seminary office you will find a gold hammer and a book that you should read. 
Leave the seminary and pick the door open on the next building up the street. This is Marius’s Office. In the first room you will find an old Druzilite manuscript. Go through the red tapestry into the lab room and you will find a bookshelf to your left. On the other side of this on the floor is a doormat. Underneath this is a key to the safe (If you have trouble seeing this, there are flares lying on the table). In the safe is Marius’s Diary, which will fulfil one of your objectives. Next to the safe is a button, which you should press. Jump up onto the table and crawl through the grate onto the street below. 
NOTE: There are a pair of gold spectacles in the Library which you can either get now or later (possibly easier) 
Luthor De Snel and the Bell Ringer 
The first house in front of you is Luthor De Snel’s house. You will be going in here in a moment. First off, go straight ahead (south) and pick the door to the so-called psychic’s house. In the back of her house on a shelf are some potions and frog-beast eggs. Leave this house and pick up the crate opposite the well. Return to the back of Luthor De Snel’s house and, using the ‘r’ key, place the crate next to the shutters. Crawl though this window into De Snel’s bedroom. Now sneak up to the light and switch it off, to make it easier to blackjack De Snel or to just sneak past him. On the other side of him you will find a floor hatch which leads to his weapon cabinet and a rather good drop of wine 
Opposite De Snel’s house is the Bellringer. You will find a note by the fire. In the Bellringer’s bedroom you will find a moneybox hidden behind some flowers and a note on the dresser which talks about where his wife’s necklace has been lost. In the kitchen you will find a gold plate in the sink and some food on the table. It’s now time to pay a visit to those Hammers’s and get the key to the well. 
Leave this area by going past the Bellringer’s house and through the tunnels until you reach the Chapel. Fire a rope arrow into the wooden ledge, climb up and pick the window to the left. Go through and grab the crowbar out of the chest. Go back to the ledge and make a running jump over to the Chapel balcony. You might want to jump off first and watch the Hammer guard pass before attempting the jump. Go down the stairs and fire a water arrow at the torch opposite. Run back upstairs and fire another one at the other torch. Follow the balcony around until you get to the altar room. Fire a rope arrow into the beam and climb down to the bottom level. In the small room next to you is a chest, which you can either lock-pick or force open with the crowbar. Inside is the well key. Open the well cover and dive in. NOTE: If you haven’t knocked Luthor out make sure that you open his shutters before diving down the well (you’ll see why later). 
The Catacombs 
Waterway 
Down here you will find brother Rowley whose drowned body has turned into a Haunt. Swim past him until you get to an air pocket. Keep going in this direction until you get to a large underwater cavern. Go left and up through the opening. Grab the water arrow and go back the way you came. On top of a ruined building to your right (south) is another 2 water arrows. Proceed east to the end of this underwater cavern until you reach another opening. Grab the water arrow here and examine the area to the south. You will be leaving the catacombs this way later. 
NOTE: Only on Master (expert level) will you have to go to all three tombs in order to fulfil your loot objectives. 
Sir Hytheance’s Tomb 
Go north now instead until you can see the top of a Druzilite’s head. Shoot a water arrow at the left torch. If you’re careful here its quite easy to sneak past her by climbing up the edge of the opening into her room. Go up the stairs and take a left, another left and proceed down a set of stairs until you get to a marble-floored room with a giant skull. Shoot a rope arrow at the short beams protruding over the statues. Before climbing up look up at the centre of the ceiling. Shoot another rope arrow at the beam here. Climb up the first rope and make a running leap over to the other rope. Climb up. If you find yourself getting a little stuck here, swivel the mouse in circular upward motions (It always works, believe me). Go up the stairs and use the crowbar on the sarcophagus. Inside is a necklace. Keep going east, passing the overhead walkway and pull the floor lever. This passageway can come in handy afterwards, depending on which order you decide to do things later. For now, go back the way you came and jump down from the overhead walkway. Make your way back to the skull room and take a right. Avoid the triangle. It contains acidic water. This is a hint for what lies in the next room. 
This next room is not that difficult once you get the hang of it. Try to make your way in a diagonal direction towards the other doorway. You have to keep on the move as the marble sections have pressure plates that trigger arrow traps. Three short jumps and one larger jump. You can stop on this one, as it has no pressure plate. Make another jump to the next marble section and your home and hosed! Save you’re game and go up the stairs. To avoid getting crushed to death, you have to make a running jump and grab onto the ledge while you’re in mid-air (there is another way you can do this also). Climb up and pull the torch, which is actually a lever. Pick the chests and grab your loot. 
Rembrath’s Tomb 
Go back to the room with the overhead walkway and proceed up the stairs. Go right (NE), passing the pyramid shaped crematorium rooms until you get to the next hex-shaped room. Press the lower eye button on the symbol that looks like % and jump on the lift-like device. When you’ve reached the bottom, make your way to the mausoleum and climb up the ladder. On the ceiling is a switch that will open a portcullis to a treasure room with three chests. Return to the lift and make your way back up. 
The Larkhale Family Tomb 
Go back to the pyramid shaped crematorium rooms and proceed down the ladder in the room to your left. Crawl through the rocky opening and jump out into the next room. Go left (north) until you get to the vine-covered tower. Go inside it and take the ladder upstairs. If your facing the window with the levers in front of you the easiest solution is to pull the levers in this order (where 1 is the number of the lever to your left): 1-3-2-5-6 
Now, go through the opened portcullis along the copper path until you get to the Masks room. Make your way to the end of the second room and collect the loot. There is a big floor-lever in the first room that will teleport you back to near the vine-covered tower. Shoot a rope arrow into the tower and climb up to the top for more loot. Carefully run off the edge and try to land on the mezzanine. 
Preparations: The Teleport Lever Key 
If you had gone to the bottom entrance of the ritual room first you would have found a note which explained why you should get this key. Continue south passing the glass floor and follow the corridor around the bend. The first room on your left is the Dark Priests room, which can be picked. Inside is the teleport lever key. In some of the other rooms you will find a health potion and a mine. 
The Seliquary 
Go back to the mezzanine surrounding the vine-tower and go east into an ancient Hammer Shrine area. The Seliquary can be found in the north room ascending from the rectangular mezzanine. There are some fire arrows + water arrows in here as well as the poor soul who got trapped there during the earthquake all those years ago. 
Rescuing Merimee 
To get to the altar room from here, you may either: 
I.	(easy-longer) Go back to Sir Hytheance’s tomb by retracing your steps to the junction, and this time go right instead. Follow this corridor until you get to the end. 
II.	(hard-shorter) Leave this room and take the stairs to your right (west). Leave this flight of stairs and take the next one to your right (south). From the top of the stairs take the first corridor to your left. At the t-junction take another left until you reach the end of the corridor. 
You will find yourself in a large corridor with druzilites using a ceremony gong to your right. Fire a rope arrow into the beam above you and jump onto the stone ledge. By following this ledge all the way round to its end you can manage to avoid confrontation with any passing druzilites. Wait until there are no Druzilites watching and jump off the ledge and run into the dark passage. From here you should try to make it behind the banner and follow this ledge until you get to the end. You can use the teleport lever key on the door here and pull the lever in this room which will take you to the top of the Altar room. 
From here there are many alternatives to how you can go about rescuing Merimee. I’ll only discuss one method here. Fire a rope arrow at the cone shaped part of the ceiling, which pours into the rings of power. Once you’re made your way onto the rings of power, fire another one onto the point of the lowest part of the ceiling. Before climbing down to collect Merimee, fire a noise arrow somewhere away from her to distract the druzilites. Grab Merimee and dive into the water to the east, taking the underwater tunnel as your escape route. You will have a couple of opportunities to climb onto dry land, which you should definitely use so that Merimee can catch her breath. After 10-15 seconds or so dive back into the water and swim into the large underwater cavern with Merimee under you’re arm heading towards the room with the catacomb gates. Now go up to the two pressure plates and put Merimee on one of them and stand on the other one yourself. As the gates open, run up and stop them closing. There is a Druzilite waiting outside here. Deal with her however you like and go and grab Merimee and make your way out of this section of the park. 
About Town 2 
The Escape 
Merimee will now wake up and thank you for helping her. But her troubles (and yours) are not over yet! To your left is a well-hidden grotto with the Bell-ringer’s wife’s necklace. Leave the park taking the tunnel. 
NOTE: The strategy behind how you tackle this last objective of taking Merimee to the place where you started may vary considerably each time. Hence I have only provided a very loose guide here. One thing to keep in mind, however, is that only the druzilites will try to kill Merimee. The guards will ignore her, but they will still be after you. 
Stay in the shadows of the tunnel and either blackjack the passing druzilites or fire a noise/fire arrow at the door of the Hammer chapel (that is, if there are any left conscious or if they aren’t outside already). This will cause an enraged group of Hammers to impart their own justice upon the Druzilites. Make your way into the next tunnel and Pembersham Street whilst trying to avoid all druzilite/guards along the way. If you haven’t done so already, there is a pair of gold spectacles in the Library. 
Now get Merimee and yourself to the gate and you’re home and hosed!