The atmosphere around Northwest Manor had always been a strange one. The Corduroys knew it almost as well as Pacifica did, and the place seemed only stranger after a crazy summer. And their discomforting encounters with the likes of Curzon Cankerblight.

The goose gave off a soft hiss of consternation as it turned in an effortless holding circle around the imposing manor's footprint, the Pines taking a look over the bird's flank as a dull hum emanated from the building's deepest, darkest centre.

"Can you… hear something?" Kevin asked.

"Kinda like some kinda…weird music." Stan mumbled, adjusting his hearing aid.

"We must go below this building immediately!" Quentin barked. "Bring on the drill attachment for my goose!"

Pacifica grimaced. "Or we could just use the elevator inside."

"Fiendish. You would make a fine congresswoman."

The goose gave off a cacophonous war cry as it came in to land in one of the enormous Northwest lawns, where tacky topiaries and the odd perturbed peacock lay in wait. Nobody quite knew what they were getting into, but were certain they'd never heard such strange music before.

It was all decidedly bizarre. They had no idea that, deep down, things only seemed to have gotten weirder. The truth was that a grand ritual, a colossal one that seemed almost unbearably large in scope, was well underway.

Underneath the building, the rattling locomotive had left the tight tunnels and burst into a cavernous sandstone chamber, as large as the Cipher Cathedral, still thumping away its impossibly loud, discomforting music from the kinks, bumps and jars in the track. Wendy and Marcus, by now, had headaches pounding almost as hard as the engine's iron pistons.

The arches and columns that surrounded them seemed outright ancient, lit ethereally with that signature, deep blue glow. From what little Wendy knew of the Corduroy designs for Northwest Manor - and she didn't tend to find looking at old blueprints very entertaining, in truth - she figured the entire hill was so emptied that this was the only way to support it. Most rich jerks had a wine cellar. This house had a damned labyrinth.

"W-what is this place?!" Wendy yelled, staring at the sidings around them.

The chamber was full of them. Railroad spurs. Strips of track, from wall to wall across the gigantic structure, each one lit by the ghostly blue tones of the town's extraterrestrial foliage.

Each spur of line, which seemed to wrap around them in a threatening encirclement, contained a long row of railroad tankers. Short, dinky little things that seemed as old as the manor itself - nothing more than big barrels stuck on top of little flat cars, smothered in dust and coiled like bullets on a belt.

Below the thick coating of age and grime, each one was firmly stencilled with a title that - to the two uninitiated - seemed remarkably benign.

Northwest Natural Enterprises & Co Ltd

R

Gravity Falls, OR

The young engine crew had to raise their voices to talk, holding onto the window frames with every buck and bump in the railroad, each one almost throwing them off of her feet. It was tiresome at best, but with every leap, there was a very real concern the huge 45-ton lump of metal could come flying off of the rails.

"Water? They're full of water? Dude, this is really messed up." She snapped, wrinkling her nose.

"At least it's not, like, something explosive." Marcus shrugged.

"Yeah, but it's still freakin' weird! What is all this junk doing underground?!"

"I- I dunno, maybe they were preppers?"

Wendy blinked. "Preppers with what, a bajillion gallons of water?!"

"Maybe they were thirsty preppers!" Marcus protested. Wendy smacked him around the back of the head as he burst out laughing.

"Jerk."

"Wendy, lighten up - rich people do crazy crap like this. Why wouldn't old-timey rich people?"

"Well, 500,000 gallons of water is still more practical than a Tesla, I guess."

"Right? It's probably nothing."

"Marcus, there's nothing, and then there's Northwest 'nothing'. The crap I've heard this Summer is crazy. There's no chance this is normal."

To Marcus - who was never the most curious, nor investigative sort - it just seemed a little odd. Rich people were always odd, and frankly, he'd never been underneath a rich-person house before. It wasn't too much of a stretch to him. Hell, if he were rich, he'd probably have a crazy mansion with a load of arches too. Who didn't like arches?

He shrugged, the engine's motion unsteadying him again as the left-side wheelset produced a distinct rumble across the shaped railway line. By now, they'd basically heard the tune several times over. As if it was the soundtrack to the entire damned summer.

Dunnnn dun dun…dundundundunnn….

The two didn't even consider bailing from the speeding locomotive. What good would it do? Sandstone floor, speeding far too quickly, increasingly turbulent railroad-kink-rumbling that rattled their teeth and threw them repeatedly from their feet…they weren't even sure where in town they were. This giant, underground marshalling yard just seemed to go on forever…

Wendy narrowed her eyes as she tried to make out the end of the line. The further it went, the darker it seemed to get…

"Every time we go down here, it feels like more of a freakin' craphouse." Stan muttered. "Ya family had less taste than Ford does in liquor, Blondie."

"Captain St. Minnegans is a perfectly fine rum."

"Bet you ain't even smoked a proper cigar."

"My body is a temple!"

"A year back on earth in a world with mobile takeout deliveries is makin' ya look more like two temples, chief."

Pacifica tried to laugh. She really did try - as did Dipper. But they were really beginning to feel the pressure of the situation - and Dipper was all too aware of what Pacifica was feeling. Although he had, all told, never really experienced being held hostage by a maniacal mother armed with a designer Stiletto, and he was eminently thankful for it.

Mabel was somewhat less tactful. She burst out into snort-laughing while leaning against Kevin for support, cackling so hard that she nearly started hyperventilating. "Hahahahah! T-two temples! That's - That's classic!"

"Maybe not the time, Mabel." Kevin gently reminded her.

"Yeah, yeah, I get it. But it was still funny." She pouted.

When they reached the floor of the underground Chamber, Dan was confronted - for the first time - by the hidden rooms he had so well-recorded in his collection of blueprints. It had always seemed otherworldly to consider on old parchment - let alone now in the form of imposing cinder-block chapels, dungeons and laboratories.

They followed an erratic trail of blue gunk - something presumably left behind by the shambling mockery of humanity that Nathaniel Northwest had twisted into - the Pines were already all-too-aware that Nathaniel was probably going to do the unthinkable - that was, try to restore the interdimensional link built from his son's empty husk. What they really weren't prepared for what the potential of what lurked at the other end of the line.

They could hear the music too.

Growing louder. And louder…

And strange, disordered chanting emanating from the laboratory…

"He's already started." Quentin snapped. "Gallop like the legs of a shrew coming upon a delicious, succulent grub!"

Gus wrinkled his nose. "Is this guy nuts?"

"He totally is. Nuts like a fox!" Mabel beamed.

At this, Gus wrinkled his nose further and looked to Kevin. "Is she nuts?"

"Nuts and a fox." Kevin grinned back, much to the overjoyed guffaws of Mabel.

They stormed into the door of the laboratory, with nary a moment of hesitation, and were greeted by the horror of a plot in motion. Where an incredible - if unhinged - scheme was underway.