There are 3 targets before you on this one: to kill some senator's son, caught on killing a prostitute, to eliminate the owner of the grotto, and to retrieve a video tape.
Watch out for the camera.
Near the place where you start a level, there are a few security cameras, so watch out. Go right and along the railing. Go under the camera when it's turned left.
Stand in the spot shown on the screenshot above and wait for the guard to approach the coke machine and sneak into his room to hit the switch that turns of the lasers ahead. Go past them and sneak into the elevator.
Go to the personnel floor and turn right. There's an agent sitting here - sedate him and take his uniform. Go forwards to the room where guards are listening to the radio. Get past them and go up the stairs to join the party.
Pass through the kitchen. Along the way, use the poison syringe on the sausage you see and take it. Find the bar and talk to the bartender, who'll give you an aphrodisiac. Use it on a Martini glass laying nearby. Go to the Jacuzzi and wait a few minutes. You'll see Chad drinking the Martini you spiced up for him, and leaving with one of the girls. Follow them to a room and wait for them to have fun. When Chad leaves, he'll go to a small balcony to have a smoke. Push him through the railing and you're done.
Go back through the red-walled corridor all the way to the "waterfall" passage. Go under it and reach the next elevator. Go up to the Studio level. The guards won't stop you.
Leave the elevator and go through the door with a blinking heart over it. Turn left, and you'll end up in a security room. The video tape you're looking for is on one of the desks. Grab it when nobody's watching.
Check the map and find your last target. Wait until he's on the balcony. Throw the poisoned sausage somewhere around here to stop his dog from barking too loud, and then push the man into the abyss. That's it for this level - you can either leave using a boat (and grabbing your suit on your way back) or take the elevator up to steal a helicopter.