Killing Chad Bingham, Jr.
The mission starts with Agent 47 on the pier. Head towards the two guards standing outside the elevator. Make sure to hug the wall as you approach the elevator, otherwise you will be caught on the security camera. Enter the elevator and ride up to the party floor. Head past the waiter and around the balcony. Go past the spas (you'll notice the target Chad Bingham in one of the spas here) and into the little cavern with the big pool. Sometimes there is a guard standing at his post in front of the door, sometimes there isn't. If there is, drop a coin somewhere nearby to get him distracted.
Run through the door and take a right. Follow the corridor around through the double doors. There will be a couple making out here, but they will not be alarmed that you are in a restricted area.
They will stop kissing when you arrive and the woman will gesture for you to follow her. Ignore her, as she is the ? person from the loading screen: the "best Agent" mentioned in the opening cut-scene by Alexander Cayne. If you do follow her, she will attempt to kill you. If you wait until she attacks and then dispose of her, she counts as one of the targets and you receive a $100,000 bonus. If you kill her right as she enters the nearby room, she counts as a civilian and no bonus is received (check the ? wiki page for more details). It is entirely possible to complete the mission without killing her, however, as she won't attack you in an open space. She will walk through the doorway into the sitting room, shutting the door behind her and staying in the room for the rest of the level.
Further down the hallway, there is a single door. Check the map; if a guard is through the next door, then wait in the room next to you for him to leave or take him out. If you check the map and a guard is approaching around the corridor, hide in the same room and avoid him (or come up behind him as he passes by for a disguise). Once the path is clear, go through the single door at the end and down the long staircase. You'll come out to a small balcony and a massive rock outcropping. If you look up, you can see the glass bottom of the spa that your target is relaxing in.
Since there are no guards that check you for weapons, you can bring your Silverballer (with a silencer) or some other silent weapon and take out the glass bottom (use a silenced SLP .40 if you need a lot of ammunition). A few innocents will be notched onto your rating at the end but it is a fairly easy method for taking out Bingham (this method will not block you from getting Silent Assassin rating, but you might earn less money due to the damage control).
One drawback to this method is that often the guards below on the pier will investigate the balcony area. If this happens, you are at risk. To be safe, get a good disguise, observe, do it when no one is looking and leave ASAP once you are done.
There is another method, that gets you a guard disguise more easily: At the beginning, go right into the Pier Inside. Enter the room ahead of you in sneak mode. Sneak up behind the Christmas guard (this guard does not have peripheral vision, so he won't see you) and sedate / human shield and K.O. him. Now take his disguise and dump the body over the rail. Turn off the laser sensor before you go to the staff elevator. In the staff floor, get out of the elevator and go into the room right of you. Close the door, sedate the bodyguard and take his clothes (nobody will find him, as long as you don't retrace your path). Now go to the staff terrace. Shoot the bottom of the spa and get back in. Take the stairs to the second floor and proceed with the rest of the mission. Alternately, you can skip the shooting part and deal with Lorne de Havilland and the female assassin first, and then kill Bingham by the method below.
On the second floor, collect the security tape before doing anything else, then you won't have to worry about CCTV. In the room with the security tape, ensure that there is only one guard; if not, harass the guard closest to you to make him go away. Now switch off the light. When the guard goes to turn on the light, quickly steal the CCTV tape and move away. The guard will start shooting you if you run or are late by even a fraction of a second.
If killing innocents isn't your thing, there is a much easier and quieter way to dispose of Bingham. Instead of going down the stairs and shooting out the jacuzzi, enter the main party room and speak with the Bartender. He will give you a bottle of an aphrodisiac which you can use to spike Bingham's martini sitting on the bar. Don't use your sedative/poison syringe, as this is impossible to do so without getting your cover blown. The aphrodisiac won't attract too much attention, considering this is a soirée held at a porn tycoon's house (a bottle of the same aphrodisiac is also available in the room in between the bar and the kitchen, you may need disguise to freely access these areas, you can drug this one, add to Chad's drink and your job is done). Eventually the waiter in the white tuxedo jacket will bring the martini to Bingham and he will promptly drink it. From time to time, a woman in a red bikini will sit down next to Bingham and flirt with him. If he hasn't taken the aphrodisiac, he will hit her and she will get up and leave only to come back not long afterwards. If he has taken it, he and the woman will go into the back hallway into a bedroom for some privacy. After a VERY long lap dance, the woman will return to the party while Bingham will go down the long staircase to the cliff side balcony to have a cigarette. This is an ideal place to kill him, as there is no one around to witness the crime. The patrolling guard doesn't travel far in his rounds and he only stops at the top of the staircase. Eliminate Bingham in whatever way you see fit, as long as his body doesn't go over the railing. Leaving his corpse on the balcony all but assures that it will remain undiscovered. It's possible to make his death look like an accident by pushing or throwing him over the railing, because civilians below will detect the body above the ice and alert the guards, thus resulting in a deduction of rating.
If you follow the method above, you can obtain a disguise either from the guard standing at his post near the door at the spa area, or you can follow the corridor around and wait for another guard. The guards in the black suits with earpieces have access to all the areas, so getting one of these disguises is crucial to infiltrating the entire grotto.
If getting one of these guards is too risky for your liking, you can enter the party once you arrive in the elevator. Before the room with the crowd of people there is a hallway marked with some "Staff Only" signs. A single guard will exit the "Staff Only" door and he will reprimand you if you're too close to the restricted area. Once he walks away, however, he is the last security person who walks around that area. Up the spiral stairs is a security room, patrolled by several guards. In this room, you can recover the security tapes in case you were caught on camera.
Inside the kitchen there should be a man in a Santa Claus costume stumbling around. He is too intoxicated to notice you are not a guard. You can spike his bottle of port with the sedative/poison syringe, or you can inject him directly. Steal his outfit and stash his body in the kitchen freezer box. The Santa outfit will allow you to enter the VIP area, typically reserved for the men in suits wearing the heart-shaped pins. While you're here, there are several sausages in the area. You can use the sedative/poison syringe one of them and take it with you. It will help later with your other target. There are also a number of kitchen knives on the counter, a great silent weapon.
There is another outfit 47 can wear which will allow him to get to the studio floor of the Grotto, one of the trickier areas to access. In the back hallway off the balcony with the Jacuzzi, there is a decorative waterfall with a secret corridor that connects to the VIP area. The Photographer is sitting on the edge of the pool at the other end of the corridor, facing away from you. Be sure to check your map before going after him, as there will occasionally be a person passing in front of the fountain, potentially spotting the attack. Sedate the Photographer with the syringe and drag his body back into the hallway between the two waterfalls. He will not be discovered and somehow he won't die, despite being completely submerged underwater. Take his outfit, which will allow you entry to the elevator guarded by the two men in suits.
If all these methods are not right for you, then follow the method above for killing Bingham up until the point where you are on the balcony. You can hop over the side and shimmy along the rocky ledge. Once on the other balcony, you will notice a box and a small passageway towards the staff area. There is a utility box here. Wait until the guard inside moves away before you attempt to break it. If you break it, the screen should divide in half and you will see a guard reacting to the loss of power. Go around the corner and wait for the guard to come out to repair. Use a coin to get him out of sight and then take him out. You can hide his body in the box, or around the other corner. This method is also sometimes risky, as sometimes the guards down on the pier happen to be looking up and see a disturbance and come to investigate.
Killing Lorne de Havilland
If you took either the guard's suit or the Photographer's outfit, then you can easily make your way up to the penthouse. You can either go back through the staff room and up the stairs past the CCTV room, or go through the party area near the kitchen, through the VIP area in the back and past the two guards standing post at a single door.
Once in the penthouse, you'll find there is a big room with a photo-shoot going on. Havilland moves between this room and the balcony off his bedroom without visiting any other locations. There is a ladder behind the cemetery scenery that leads to the catwalk overhead. Follow the catwalk to the right (if you're facing the beach scenery) and rig the lighting fixture with an RU-AP mine. Once Havilland goes beneath it, you can detonate the mine and drop it on him. It is important to note that not only will the lights kill Havilland, but there is also a chance they will kill one or more of the models. After the bomb goes off, there will be chaos and everyone will start running around. Your suspicion meter will immediately go up, so it's best to detonate the mine in a spot where you won't be noticed.
Alternatively, you can kill Havilland on his balcony, a much more secluded area. Make sure to time your movements wisely, as guards regularly patrol the area near his bedroom. This is a restricted area and no one besides Havilland is supposed to be there. There's a bathroom just off of Havilland's bedroom where you can hide out from the guards. It's important to use stealth when following Havilland, as he is extremely paranoid and will call for his guards if he realizes you are following him. Once he is on the balcony, drop the sausage you took from the kitchen. The dog will immediately run for it and eat it. If you poisoned it or injected it with sedative, it will act pretty quickly and take the dog out. This eliminates another level of security, as the dog will bark and alert the guards if you attack Havilland. Once the dog is unconscious/dead, eliminate Havilland however you like.
The dog does not count as "damage control", but it can easily ruin your day if you are stealthy player, as it otherwise counts as a 'witness' if you kill de Havilland without taking care of the dog first.
In cracked versions of Blood Money, problems with using the drop key and placing RU-AP mines have been reported in this level. If you use a cracked version, do not despair: start the mission with a silenced gun. Kill de Havilland on the balcony and shoot the dog. Strangely, your rating won't be affected unless you fire another shot. The only drawback is that you MUST use the aphrodisiac method to kill Bingham if you want an SA rating, but I think the trouble is worth it :) .
Make sure you have the video tape before escaping. It's in a security room just off the photo studio. Getting the tape will require a little finesse, as there can be up to two guards in this very small room. One guard stays in place while the other passes through as he makes his rounds. The tape itself is on one of the desks. The best way to steal the tape is to either throw a coin or (even better) turn off the lights. Either way, make sure the first guard is distracted and the second one isn't about to walk through the room.
Now it's time to make your exit. You can either take the penthouse elevator up to the roof and take the helicopter (if you take this route, make sure you get rid of your guns, as a guard at the door will stop and search you using the metal detector, no matter what disguise you use), or you can go back to the start and use the boat.