Thunder, lightning and buckets of rain hammered Gravity Falls even harder that very next day. It was so substantial that the rainwater leaked through the Crawlspace's ceiling, with every thunderous boom echoing on its clay-and-earth walls.

A stalacite fell and almost skewered a gnome as he pushed a shopping cart full of baked beans.

There was no doubt about it - the weather was worse than ever. Above the surface, the town was drenched in darkness. A circling tempest of lightning, thunder and pouring water turned the streets into rivers, and the lake into… uh… an even bigger lake.

The stores were all closed once again, sandbags piled up in front of their doors just in case the river or lake managed to burst their banks. Neon signs and outdated lamps glowed and flickered, threatening to switch off with every crash of thunder.

Lamposts rattled and shook, cables and wires occasionally breaking free from their poles and flickering in the wind like a whip. Every building creaked and groaned as the wind threatened them, pushing, shoving and groping at their mortar with furious glee. The sign for the theatre broke free of its mount and crashed into the neighbouring gourmet pancake mix store, creating a spectacular show of sparks and breaking neon.

It was no mere summer storm - it was a growing Summer cataclysm. The gales blew, whistled and roared through the iron beams of the Wentworth bridge, the Northwest Manor lost several heavy, solid slate roof tiles which flew into the town like paper aeroplanes in the breeze of a desk fan. Debris fell from the cracks in those enormous, floating cliffs. The Tent of Telepathy, long disused, was thrown into the heavy winds and disappeared into the dark, swirling skies.

KRAKA-FOOM

Lightning struck one of many towering pines in the forest, sending it falling to the ground in a burst of orange flame and spark. The giant cabre smouldered and glowered as it crashed to the rails of The Awesome Express, just outside the mystery shack.

At least - for once - the little engine had escaped destruction.

Thankfully, Soos, Melody and Abuelita were all quite secure in the confines of luxury retro-style aluminium and steel.

"Dude. This ain't like a normal storm." Soos said over the thundering pitter of rain on the Airstream's shell.

"Huh?" Melody asked, flipping her magazine's page.

"I said THIS AIN'T LIKE NO NORMAL STORM, DAWG!"

Melody huffed, smiled, and sat closer to her boyfriend in order to hear him, cup of cocoa in hand and head resting on his shoulder. "It is pretty rough. Like the town's eating itself or something."

"Do you think it'll be alright?"

"You mean 'do you think the Pines will be alright.' Right?"

"Dude, they're like, my best friends, bro."

"Honey, underground is probably the safest place to be."

"You're my favourite little sweet potato, Melody."

Melody beamed. "I yam?"

"You totally are- oh! Hahaha! Yam! Like a - like a sweet potato. That's - that's pretty good."

The warmth, tacky techno decor and stacks of video-game collector's editions felt like a world away from the circumstances deep underground. If it was truly the safest place to be, it was hard to believe it.

Deep under Northwest Manor - timed almost perfectly to the impossibly harsh storm that had broken out over the town - the manifestation was complete.

Nathaniel Northwest was home. Raised from the very Earth of the Oregon Valley he had once so fiercely commanded.

The cinderblock maze of corridors and halls were filled with groaning, snarls, and roars of anger. The righteous fury of a man long out of his best-before date. Preston approached the laboratory door with a certain level of hesitation.

"Are you sure you want me to do this, darling?"

"Preston. I want my daughter back."

"V-very well." He huffed, opening the airlock handle to that great iron door.

The door groaned open, casting the laboratory in the first light it had seen for twelve hours. A moist spot remained in the centre of the room, stained in a deep brown colour that resembled a foul-smelling, curdled molasses.

Flies were beginning to gather around that smear of what could only be dubbed human gunk.

"Great-Grandfather?" Preston said, holding up his lantern.

A shallow, throaty gurgle erupted from a corner of the room. "Mmrugh… bastich."

"Great-Grandfather, is that you?" The Northwest patriarch repeated, taking a further step.

Illuminated by lantern light, there, in the corner, a crooked man with a long beard and bushy moustache sat, crouched in a set of clothes that Preston had left purely for the purpose. However, Nathaniel's paintings had illustrated him as broad-shouldered…

Clearly, in the later years of his life, this had most definitely not been the case.

He was thin, wiry, with discoloured skin and yellowed eyes, covered in the sagging, outsized suit, completely barefoot. He was greyed and…

And the ancient creature was savagely chewing on a dead rat.

"Oh, god," Priscilla whispered.

"Great-Grandfather! It's a pleasure! I'm your-"

"Yer don't- yer don't git ta talk ta me until ah've finished this…bastich." The foul figure interrupted. A fly landed on his crooked eyeball and he barely even noticed. He himself didn't smell, per se… just looked ill. Terribly ill, terribly wonky, terribly crooked.

Preston had it in his head that they'd get Nathaniel Northwest in his prime. Instead, they had raised him as close to death as the man had ever been - a crooked, quivering mess of a creature that was ruled by paranoia and fear.

And that was their secret weapon?

Priscilla groaned inwardly. In her mind, all was lost.

"Well now, Sir, we could get you a much better meal-" Preston ventured.

"Ain't no wrong eatin' on rat." Nathaniel snapped back. "Ah've been eatin' these here rodents since that triangle tried ta steal mah eyeballs!"

"We need your help, great-grandfather. Urgently."

"Then yus can wait until ah've got mah bearings." He replied, firmly. "Ah'm a powerful man."

"That's why we-"

"Ain't no reason a Northwest would raise me unless there wus…" The scrawny figure continued, unabated, narrowing his eyes. "...Family issues."

"That's exactly right."

"Well then, that's differ'nt." Nathaniel replied, throwing the rat carcass to the floor and wiping his mouth on his cravat. He stood up - almost valiantly - and glared at Preston. Were it not for his marbled, greying skin, or his yellow eyes, or pale, decrepit appearance, he'd look like one of his flattering portraits. "We's better git down to talkin'."

"It's an honour."

"Ain't no trouble. Who's the lady-britches?"

"That's your great-grandaughter-in-law-"

He spat out a piece of rat gristle. "Looks cheap."

Priscilla spluttered as, without another word, the old man hobbled out of the laboratory and began making his way to the concealed elevator, back to the upper echelons of the Northwest Manor.

Preston cringed. "Oh - um - Sir, we don't- we don't live in the… mansion… anymore."

There was a pause. Nathaniel stood still and rolled his shoulders, without casting his great-grandchildren a single glance. His hands - wiry, boney, and blotchy as they were - clenched into fists.

"Well shucks," He said, darkly. "Seems we got even more serious issues than I thought. Mayhaps we just talk here. Sounds like ah'm due some real disappointments."

"I - I suppose you are." Preston huffed, tenting his fingers together. "Come, come, I'll - we'll pull up some chairs."

Up above, a particularly strong bolt hit one of the many lightning rods that McGucket had installed on the Manor's roof. The storm was every bit as furious as the newly raised Northwest master. And, just as he was, it grew more seething, hateful, and violent with every passing moment.

Things were only going to get worse before they could get better.