Yeah… no.
The walkthrough itself is hidden here because of how long it is.
Summary
Beginning at the default starting location on the motorcycle, walk along the path (you’ll be walking for the entire playthrough, never running) and move off to the side to where you can go behind the bushes and hop over the gap in the wall. Cross the little creek, staying crouched to avoid those two assholes near the gate from seeing you until you’re near the boulders on the other side of the creek, then you can stand. Make for the gap in the wall ahead that leads to the bushes near where vehicles are parked, sneak past the front of these vehicles, staying out of site and staying crouched, because this ET has an extra guard who will come down the stairs near the front entrance and see you if you stand. On the other side of the row of parked vehicles and luggage, hop the small stone wall, cross behind the bushes within, then hop the low wall on the other side, heading for where the deliveries are, and your hidden stash. Obtain your tranquilizer pistol, then head back the way you came, staying near the wall of the manor on your right. You’re going to go around the corner, into the bushes right below the window that leads to the butler’s office and the staff/laundry area. Climb through that window.
Once inside, head toward the open door leading into the staff room and close it without being seen, then open the other door nearby, heading out into the hunting hallway where the private investigator stops during normal Dartmoor gameplay. There’s a maid dust here; sneak past her, past the staff room door (coming back here shortly), and around the corner ahead. After turning the corner, you’ll see two coins on your right; these coins are going to be your best friends during this playthrough.
Ahead are two closed glass doors and to the left is an open closet. Head to the doors and open them, there’s another dusting maid on the other side; keep to the left side of the doors as you open them to minimize the chance of her seeing you. As soon as you open the double glass doors, turn around and walk toward the open closet until you are lined right up with the door. Turn around, throw a coin on the ground in front of you; if you did this quickly enough, the glass doors should still be open. The instant you hit the button to throw the coin, turn and move into the open closet. The main should have heard the coin land and go to investigate. Inside the closet, there’s a black box on the opposite wall of the cabinet that can be hidden in; wait until the maid picks up the first coin, and as soon as she turns around, throw the second coin on top of the black box – so long as she’s not out of range or the doors haven’t closed behind her, she’ll hear the coin land. Duck into the cabinet behind you and equip your tranquilizer. Once the maid is in the closet and is reaching for the coin, step out and shoot her with it. When she collapses, reload your tranquilizer, collect the coins, then leave the closet and close the door behind you.
If you have moved without hesitation up to this point, even while just walking, then Jack will either have walked into the kitchen near where that maid was while you were dealing with her, or is doing so at this point, so use instinct to check first before proceeding. Pass through the glass doors to where the made was, being careful not to be spotted while walking past the door by the wandering maid within. Once on the other side of the door, look inside, see one of the servant guys mopping, and throw your emetic grenade at his feet. Close the door so you won’t be seen when he and the maid turn to look in your direct, then retrace your steps back to where the staff door was before, crouching when you turn the corner to avoid the first dusting maid from earlier.
Inside the staff room, grab the wrench leaning against the wall in front of you, go around the corner to where the toilet is, and place one of your coins against the wall, between the mop and lead pipe located here. The servant guy from earlier should be arriving now and start puking into the toilet. Move behind him, as far as you can go, until you’re in the corner where the wall and lockers meet, with the mirror above the sink next to you. Have your tranquilizer ready. Once he’s done puking, he’ll spot the coin and go for it; if you placed it right and are standing as far back and to the left as you can, he won’t see you. As soon as he goes for the coin, shoot him with the dart. He should fall in a way where he won’t be seen without someone walking all the way into the room. Take his outfit and leave him where he is.
Head back to the spot where you were when you threw the emetic grenade, and exit the manor through the side doors here. Go down the steps and to the left, all the way around to the back side of the manor, and in the corner where the shovels are hanging is the ladder to Zachary’s balcony. Climb up, move over to where the gas heater is, and wait until the maid up here and anybody inside the room are not in a direct line of sight of you, then cause a gas leak with the wrench. Retrace your steps and return to where the kitchen is. You did all this now so as to use up the time that Jack and Mr. Burk talk on the second floor, so that Jack is headed back to the first floor by the time you take care of the next bit of business.
Now, this is the part where I had to do a lot of restarting, because the timing is tricky, and as mentioned, I didn’t have the patience, but you need to make it so that the maid inside the kitchen doesn’t spot that you’ve turned the left stove inside the kitchen off. Throwing coins might bring a guard in from outside since there’s an open window, and the flooded sink might not line up with the timing as well as hoped. Without lockpicks, and no using keys or crowbars per the HPP, you can’t get the banana in the staff room locker. However, since you’re dressed as a staff member, you can go most places. Here’s where I’ll write specifically about what I did because this is where the road may fork among individual players; this part is why I don’t consider this playthrough “perfect,” because although I adhere to the HPP, this part is kinda sloppy. So, on this playthrough, I headed to the cemetery and grabbed a rake that’s laying in there. I walked back to the kitchen and used coins to lure the maid out of the kitchen into the hallway near the delivery exit doors from earlier. I placed the rake on the ground behind her and when she turned around to return to the kitchen, bam! I entered the kitchen and shut the door so she couldn’t be seen.
Unfortunately, Jack was in the kitchen and had prepared a plate of food, so he picks it up and starts heading toward the very door I just closed. He opens it, sees the maid, drops his plate (important), and runs outside to get a guard. While he’s doing that, on a hope, I head to the leftmost stove and turn it off, then cause a gas leak. I’m thinking chances are good I’ll have to restart again. However, since Jack dropped his plate, as the guard is reviving the maid, he walks back into the kitchen first, sees the stove is off, and I know I’ve got him. He’s doomed at this point, so I grab the mop for the blend in option, and wait a few seconds. Sure enough, the bespectacled bastard blows himself to kingdom come, I stop blending in, and head to the staff room and hide in the laundry bin until everything calms down, just to be sure I don’t run into an enforcer I didn’t expect. During the panic, the staff guy’s body is found and revived when Jack’s body is moved. Wait until everyone goes back to how they were, then go into the kitchen and grab the cigarettes Jack dropped.
Now, we’re back into a general walkthrough, since no matter how you managed to keep the maid from spotting the stove (without killing her or KOing her with any melee), the next part you’ll proceed pretty much without variable, save one that we’ll get to in a minute.
Once you have the cigarettes, return to Zachary’s balcony through the same path as before, and wait until Mr. Burk is not inside, assuming he is at the time you get there. Here’s the one variable: If Burk is inside, he might take the guard inside with him, at least for a moment, but if not, there will be another maid and a guard inside Zachary’s room. If Burk is inside, wait for him to leave and the guard to follow, and while they’re gone, and the maid inside is turned away, go in through the balcony doors and to the left, where there is a spot near a potted plant for the cigarettes to be placed. If Burk is not inside, and the guard and maid are both there, wait until neither had direct line of sight and throw a coin as far as you can to make sure the guard goes for it while facing away from you, and the maid goes back to what she was doing, still facing away from you, then place the cigarettes.
After that, get the fuck outta dodge. You may use coins and such to bring somebody to the maid you knocked out in the closet in order to set everything just how it was again, and while I prefer that, it’s a negligible part of the HPP, and you can skip it if you wish. Either way, return to the staff room, place the wrench back (you can’t put it exactly as it was, but everyone will just assume that it fell over after the explosion in the kitchen), and reclaim your suit from near the toilet. Crouch and sneak out of the staff room into the hunting hallway, slipping behind the maid dusting here.
Retrace your original steps back to the window near the butler’s room (watch out in case the staff/laundry area door is open again here), and climb out. Wait until the guards outside are facing away, then sneak back to the low rock wall near the bushes that you came through earlier near the row of parked cars, and drop down to the ground below. Head toward the creek, and around the spot where the boulders are, crouch to avoid being spotted. Hop back over the wall in the same place you originally did at the beginning, and carefully walk back toward your motorcycle. At some point between hopping out of the window and closing in on your motorcycle, if you did not screw around, Burk should blow himself up with the cigarette near the gas leak you caused to the heater earlier. Hold back a second to make sure Silent Assassin rank is still in place and no one else died in that second explosion. If it did, or if anything happens after either target dies that messes with the whole thing, do the disconnect restart to begin again. Otherwise, hope on your motorcycle and exit the mission.
There you go: Silent Assassin, two accident kills with explosions, all while adhering to the Heisenberg Parameters of Perfection. There can be some variations on this particular walkthrough; I know I did some. But that’s an example of how to do it.