One of the empty rooms was now Dipper and Mabel's own, furnished with a pair of simple beds but not much else. The other twins were busy doing something with the house – though exactly what, they wouldn't say.

"Is it just me or did Grunkle Stan seem nervous?" Mabel asked, bouncing on her bed to test the mattress. It squeaked very little, but provided a lot of firm resistance. "Whoa. This thing is way better than what I got at the shack."

Dipper, who had been reading on his own bed, set the journal aside and recalled their goodbye. "I guess? He seemed kinda relieved too, though. Weird. Can you be both at once?"

"Huh. Maybe he's worried about us, but he's happy we're safe?"

"You're probably right." His thoughtful eyes went to the window. "Wonder how long we're gonna be here."

"Ah, it won't be long, bro. Between my awesomeness, their superpowers, and your whatever it is you've got, we'll have this handled in no time!" She ceased bouncing by falling spread eagle onto the mattress and stared around with a huge grin. "...I need posters."

"Speaking of them, I wonder what they're doing." He leaned toward the door and listened. "You hear anything?"

"Nope!" she replied happily, not even trying to listen. She was still making faces at the empty walls above her bed. "Relax, bro. I'm sure they'll tell us when they're finished."

Winter poked her head through the doorway, looking at the window before regarding either of the Pines. "Don't mind me," she said quietly. "I'll be done in a second."

"With what?" Dipper's face screwed up as she snapped a few times, though what she'd changed wasn't immediately apparent. "Um...?"

"Just thickening the panes," she said, running her fingers over the glass to check. "We've taken out all the doors except one. If anyone wants to get in, they'll have to come through the front. And at least one of us will be waiting on them."

Dipper stared into space while processing her words. "Huh. That sounds ominous."

"For good reason." She issued another snap; this time the window frame changed from wood to steel. "There. That should be enough for now."

"Hey, let's go back to the thingy!" Mabel asked as she sat up. "Maybe there's some stuff we missed 'cause the Sheriff interrupted us."

"Honestly, I'm surprised he hasn't come back to try and arrest us again." He slid off the bed and walked over to Winter. "I'm kinda with Mabel, though. I wanna get this over with as fast as possible."

She nodded in agreement. "So do I. You can come with me to the graveyard tonight to speak with Wilhelm."

Mabel hid her eyes and groaned. "I shoulda kept my mouth shut." Something in Winter's statement was off, however. "Wait... just you? What about Summer?" she asked, dropping her hands.

Winter rolled her eyes about in search of a suitable lie. "She's going to stay here in case anyone attempts to break in. I'd rather not walk into an ambush when we return."

"Ha! Man." Dipper ran a hand through his hair, eyes full of anxiety. "I didn't expect to spend my Sunday running from the federal government. Sheesh."

"Mm." Winter turned on her heel and moved toward the door. "At any rate, my plan is to leave after sunset."

The Pines followed her out. "Then we'd better eat something!" Mabel chirped happily.

"You always say that. If you weren't so hyper you'd be huge," Dipper muttered. He assumed she hadn't heard it – but he was wrong. He shrank back under a withering glare. "Uh..."

Winter ignored the growl, lunge, and squeal of terror that happened behind her and pressed on to the living room, where Summer lounged on the couch. She tossed a spherical object idly in her hand while watching TV. "All done?" she asked, looking around. The cardinal and its cage were missing.

"More or less," she confirmed, not bothering to avert her eyes. "What are Dipper and Mabel doing in the hallway?"

Winter sat with her, eying the screen. "Sibling disagreement. They want dinner before we start tonight."

"All right. I'll 'cook' something in a bit." Her ruby eyes were pensive.

"What?"

Summer let the sphere drop into her lap. "I'm not sure I like splitting up," she admitted, hugging herself lightly. "We always go together."

"I know, but we'll cover more ground this way. The sooner we're done, the better."

Her gaze went to the Pines, scuffling in the hall with equal parts facetiousness and anger. "Do you think it'll ever end for them?"

"That's..." Winter hunched over in thought. "That's a good point. We might have to inflict just enough damage to get them to back off on a permanent basis."

"How much damage would that be?" Summer asked, finally turning away from the fight.

Winter had no answer. Instead, she rose and walked over to end the argument. "Excuse me, but..."

Mabel had Dipper on his knees and by his mousy locks. "He called me fat!"

"I'm sorry! Have mercy!" he begged, hands flailing about. "Agh! Let go of my hair!"

She separated them with her power and frowned. "He also apologized. Come on, get up."

"Fffffffffffffffffffffine." Mabel stalked off toward the couch. "Hey! Where's the bird guy?"

"I turned him into something easier to deal with," Summer replied, pointing to the sphere as she tossed it again. "So, what's for dinner?"

"Pizza!" Dipper blurted out.

"Tacos!" Mabel countered. They stared at each other for a few seconds; Winter got between them to head off another fight.

"We can have both," she advised, rubbing her eyes. "Now play nice. There are enough enemies to deal with without you two at each other's throats."

"Ooo! Could you turn the TV into a toaster?"

Winter – on one end of the couch with her sister – wouldn't even look at Mabel, who was seated on the other end with Dipper. Her eyes were dull with resignation; the girl had been interrogating them since after dinner and that was nearly three hours ago. "Yes," she sighed.

Mabel's smile was absolutely massive by now. "No no wait, could you turn the TV into a toaster that spits out money?"

"Probably..."

"Could you turn the money into dragons?!"

"Mabel!" Dipper snapped, slapping the journal shut. "Stop harassing them about their abilities! Geez! No wonder they were so afraid to tell anyone!"

"Exactly," Winter sighed with relief. "We're not wishing wells."

"I'd really like a toaster that spits money dragons though," Summer admitted while rubbing her chin. "It sounds fun."

"Mm." Her eyes went to the window. "I think it's dark enough to head out."

"Oh boy." After straightening his hat, Dipper rose and moved a little to stretch his legs. "So, are we driving or flying?"

His tone was jovial – at least somewhat – but Winter's answer was quite serious. "Flying. I don't want people to see the car and get curious again."

Mabel rubbed her hands together gleefully. "This is gonna be the best thing ever." Of course, what would come after the flight made her face soften with distaste. "And then it's gonna be the worst thing ever. Blargh."

Winter gave her an awkward pat on the shoulder. "We'll make it quick." She nodded to her sister, then toward the hall. "Excuse us for a second."

"What is it?" Summer asked lowly after they'd walked away, glancing over her shoulder as the Pines started their own little conversation.

"There's a chance someone might be waiting for you when you get to the shack. I know we didn't see anything on the news, but pressure might have kept it out of the media. Be ready."

"Right," she nodded firmly. "I hope there isn't. I don't want to hurt anyone."

"Of course. But don't let them stop you, either."

"Oh, no one's going to stop me." They shared a steely look. "Anything else?"

Winter's brow furrowed. "If you're going to fly, no wings. They'll glow, and the last thing we need is that kind of attention."

"Okay." They returned to the Pines, bearing smiles of varied intensity. "All right! Well, have fun. I'll make sure everything is in order here."

"Fun? What fun? There's no fun. This is the anti-fun. It's... nuf," Mabel complained weakly. "But I guess it's time to get it over with."

Dipper nodded with a sigh. "Yep. Let's just do this. Can we go check on Wendy and Soos first, though? Not being able to call makes me kinda anxious."

"Of course," Winter replied. "Sister... see you later."

Summer waved as they slipped out the front door, then observed through the window as they went around the back. "All right. I'll give them a moment." After turning off the TV and darting through the house on one final sweep just in case, she too went outside and made her way to the backyard. The rear of the property was bordered by thick forest, almost indistinguishable from the night sky save for the lack of stars. She searched the air for her sister and the kids, but they were already out of sight. With a deep breath, she detached from the earth and ascended, higher and higher, until Gravity Falls was a loose collection of dim yellow lights below.

At this height, the trip to the Mystery Shack was a matter of pointing herself at the hum and accelerating for a few seconds. She overshot the noise by a bit, but found herself more or less right over the old house. Without a moon to cast light, seeing if anyone was around was difficult; instead she dropped into the woods nearby and approached on foot to be safe. The main entrance soon came into view through the trees. A few lights were on inside, and the old red sedan sat in the free parking area. Nothing appeared to be amiss – but she kept on guard and crouch-walked into the clearing. Her eyes darted around at every movement. She only relaxed after making it to the gift shop door, only to find it was locked.

Her first inclination was to snap it out of the way and then restore it once she'd entered. However, the concept of being watched by some formless group made her uneasy about shows of power – and being separated from Winter under such circumstances didn't help. Therefore, she pressed her palm against the keyhole and used the strange black material to gunk up and defeat the mechanism. Upon walking into the shop, she found the door to the living room open and poked her head around the frame.

"Hey," Stan greeted, sitting in the recliner and illuminated by the light of the old TV. He was still clad in his usual suit, but had his tie loosened and blazer unbuttoned. "Where's your sister?"

"One of us is going to stay with the kids at all times to make sure they're safe," she replied, walking over to him.

"Heh, good idea. I, uh..." He paused to rub the back of his neck. "I really, really appreciate it."

She gave him a pleasant nod. "Don't worry. They're in good hands."

He rose from the chair and walked off, coming to rest in the entryway with his back to her. "I'm just worried someone might try to murder you over this when it ain't your fault. It's mine. And if someone hurts them I swear..."

"They won't. I promise. We promise."

There was a quizzical glimmer in his eye as he looked back at her. "How can you guarantee that, kid?"

"I wouldn't if I couldn't back it up," she replied quietly, almost staring him down.

"All righty. You got secrets too," he said after a brief silence. "Par for the course in this town. Follow me." He moved into the gift shop and over to the old vending machine, placing himself between her and it. She could hear him tap on the keypad, but made no effort to peek. The machine slid away from the wall slightly. "All right. What you're about to see doesn't officially exist. Everyone related to it is dead as a doornail or got bought off by the U.S. government."

"I assume you fall into the latter category?" Summer asked, watching as he pulled the machine open like a door, where it revealed a hidden corridor. "Otherwise, you look pretty good for a corpse."

Stan snorted at her quip. "Heh. Kinda." He motioned her into the passageway. "You first. I gotta close this back."

"What are you going to show me, exactly?" she asked, head tilted at the dilapidated nature of the stairwell. An elevator ahead caught her attention – as did the slightly increased clarity of the persistent hum.

"Oh, you'll see." Stan entered another code on the keypad beside the doors, then pressed a button. They slid open. "Kind of a tight fit in here, be careful."

Summer had to contort her way past him to get in. "I see what you mean." She looked up as the descent began. With each passing second the hum became louder and clearer, though it didn't reach the shrieking power of the pit's voice, even after the elevator came to a stop and the doors opened. As Stan moved aside, she found herself looking at a narrow chamber full of technical equipment. "What is...?"

"This is the station the United States Army used to use monitor all the weirdness in Gravity Falls," he explained, waving a hand at a couple of screens as he walked past. "They left after the..." A pained look swept across his eyes, but Summer was too distracted to notice. "Forget it. In exchange for keepin' it quiet, the government helps me, you know, financially. And also they may or may not have helped me legally. I can't confirm or deny being wanted in a non-zero number of South American nations."

"How did you end up with it?"

"It, uh, it passed to me from my brother." They had arrived at a desk with a large control panel. Through a plate glass window sat a huge metal triangle with a circular hole in the center. Bright bluish-white light poured from the opening. Two pairs of metal circles were embedded in the stone ceiling and floor before it. All the edges were dotted with aquamarine-colored lights, and a set of strange symbols edging the circle flashed with colors at random intervals. "Here it is. Gravity Falls' biggest, most ridiculous secret."

She barely heard him; the hum was at its loudest now, though not unpleasantly so. Finally there was a source to pin to the noise. Almost unconsciously, she went through the nearby door and drifted over to the device, gobsmacked by the undetectable sound it made. "I hear you," she said to it, standing next to a large lever on the floor.

"Hear, uh, hear what?" Stan blinked, glancing sideways a few times. "It's in scan mode. It would be makin' a lot of noise if it were fully on, but it ain't."

"It's humming!"

"No it's..." Something in her demeanor made him feel uneasy. "Anyway, this is the portal they built back in the forties."

Summer could not tear her eyes away from the hole in the triangle. "What happens if you turn it off?"

"Huh? I feel like we're havin' two different conversations here." However, he obliged, pulling the lever back with no small amount of effort. "There. It's off."

She already knew that. Besides the lights going dim and the hole going dark, the hum had suddenly disappeared. "Now it's quiet."

Frustrated, he crossed his arms and peered at her. "No, it was already qu—hold on. Is there something I need to know?"

Her gaze landed on him at last. "Turn it on. All the way on," she said with a smile.

He denied her, hands waving. "Whoa-ho-ho-ho no. That would attract some real bad attention, lady. You know how hard it is to get the US intelligence community off your back? It's not like you can just send 'em a fruit basket with a card."

"US intelligence community?" Summer's expression darkened. "Wait... is this the portal?"

"Yeah. Why? There's more than one? 'Cause—uh, 'cause if there is, there ain't an expired-enough apple cider on this planet to drown my sorrows."

Face screwed up in thought, she looked back up at the device. "So then... this is where the magic came from?"

Now Stan's amazement matched hers. "You know about the magic?!" he exclaimed, walking over to her. "How?"

She regarded him with an awkward frown. "Um... there are a few things about Winter and I that I think you should hear. Let's trade some secrets, hmm?"

Mabel and Dipper needed nearly two minutes to shake off the tingles that came with Winter's telekinetic grip after they'd arrived in the graveyard, but it wasn't just their problem. Wendy and Soos were also doing the odd dance.

"Why did you come with us?" the boy sighed, brushing at his arms to chase off the itch. "You guys were fine! They didn't even know you knew."

"Dude, we ride together," Soos replied, quoting Mabel's words at their meeting. "Even if it means facing off against the... hoo. I might—I might not have fully thought this through, dudes."

"Yeah, well, I guess I just don't care anymore," Wendy added, panting a bit from the ride. "Maybe I wanna find out if I've got powers too, you know? Man, that'd make my life so much easier."

"It's not as glamorous as you think," the blue-eyed woman advised, waving for them to follow to the abandoned corner. For a moment she tried to figure out why the atmosphere seemed quieter, but Mabel's agitation stopped her from giving it too much thought. "Come on. Let's go."

"Yaaaaay," Mabel cheered sarcastically as they all fell in and start walking. Even her hand motions were cynical. "Let's talk to literally the worst person ever! Frack."

"I couldn't agree more," Wendy sneered.

This time, there was no chill occupying the space, no whispers to tease anyone's ears. All they found was quiet and uneven grass, waving in the night breeze. "Okay, so where is he?" Dipper asked, tipping the bill of his cap up as he looked around. "Are we in the right spot?"

Winter nodded a few times, also glancing around. "Yes, we are. Maybe he doesn't want to talk to me."

Mabel's head tilted back and forth. "He doesn't. Someone just said he doesn't. If this ain't Soos or Dip messin' with me, I'm about to lose my-"

"What do you want?" a wandering voice demanded, distorting in volume as if the source was weaving between them. The spirit of Wilhelm Seifert swirled into view, bringing the icy fog along. "I told you, I've nothing else to say," he added, eying Winter with distaste. "Take your magic and friends elsewhere."

"Don't you tell us to buzz off!" Mabel exploded, storming to the front of the line and pointing right at his ghostly nose. "How could you?! How could you kill them? They couldn't defend—I just—ugh! You evil man! Evil evil evil evil!" By the end, her words were more like dry, bitter sobs. She turned to Winter, eyes halfway hidden by a sweater sleeve. "I can't do this, yo, I'm sorry. I wanna go home."

"Young lady, I understand how you feel," Wilhelm offered gently. Out of instinct he tried to put a ghostly hand on her shoulder; Dipper didn't like this much and stepped between them with a glare. The spirit withdrew with a nod. "I assure you, there was no joy in what I did, but it had to be done. Humanity was not ready to know! And I... I could not let them live."

"You don't know what would have happened!" Soos yelled, voice as harsh as any of his friends had ever heard. "They might have been total bros! Real life wizards, dude! They coulda helped!"

Wilhelm was unswayed – and looking melancholy. "No. I guarantee you they could not have helped anyone."

Wendy was nearly as emotional as Mabel, but managed to put up a cool front. "You stole my aunt Diana from me. You said you saved the world? All you did was blow a hole in the heart of Gravity Falls because you were too scared to wait and see!" she said, anger increasing with every word. "Give us a why, man! Give us a legitimate why!"

If she had been expecting indignant rage from the proud German, he completely failed to deliver. Instead, Wilhelm drifted all the way back against the corner of the wrought iron fence and floated in silence. Dipper, sensing Mabel was ready to ignite once again, pulled her into a tight hug. He hoped Winter would use the chance to take command of the conversation.

After a moment, she did. "The United States government sent an assassin to murder my sister and I," she called to the ghost.

He looked up in confusion. "Why? Was I correct? You're really not children of the portal?"

"We already told you that," she replied tersely, a hand on her hip. "We saw a man named Dietrich Seifert in a file about... never mind. Family of yours?"

"My elder brother," he nodded, drifting back their way. "But I can't tell you anything about what he did."

"You mean his role in Project Apollyon?"

Shock overcame his visage. "You do know! I see, I see, you're just keeping your friends in the dark for their safety. Of course." He returned to them with a light smile. "Although, I suppose they're not in the dark now."

"We weren't before, man," Wendy corrected him with a glare. "You told us about the portal last time."

"Yes, but I did not tell you the Army's role in building it. And perhaps I shouldn't, there are children here."

"Talk!" Mabel roared, eyes shining with rage as she broke away from Dipper. "If I'm gonna stand here and be around you, you incredible fiend, then you're gonna spill the beans so we can go! Now start singing, buttface!"

"Mabel!" her brother said gently, taking her by the hand. "Calm down before somebody hears us!"

"No!" It took Wendy's help to bring her back to the group, though she fought and snarled all the way.

Winter left them and walked right past the spirit, who tracked her movements with uncertainty. "Miss?" he said, eventually pursuing her to the corner. "What are you doing?"

"Giving Mabel room to breathe," she said quietly, leaning on the wrought iron. "Listen, you can't confirm that the portal is still inactive, can you?"

"Admittedly, no. My detection range is limited without a corporeal form." He floated around her in an idle circle – though they noticed he never tried to pass through the iron fence. "However, there were multiple agencies dedicated to keeping our secret, even back when I turned myself in in 1963. If the portal were open again, I believe I'd see the signs."

"Mm. How did you detect us, exactly?"

"Exposure to the portal granted a few of us limited usage of its power. From then on, we always somehow... knew, where the others were." Wilhelm turned his back on her. The wan light he gave off seemed to become even gloomier. "I signed up for Apollyon to assist my brother. I knew the risks. But there were those in Gravity Falls who did not – nor had any chance to refuse."

Winter cocked a brow. "What do you mean?" She walked toward him when an odd sound reached her ears. "What?"

"My son," he wailed quietly, facing her once more. "My son. My brother's son. Many of the researchers' children. The magic did not affect them as it did us. It caused them... so much pain. I had no choice."

She didn't need clarification. The look in his eyes was one she'd seen many times before, gazing back at her in the mirror. "You killed them?"

"Dietrich couldn't bear to euthanize his child. Can you blame him? I don't know what gave me the strength. My sweet, sweet Kaspar... and Albrecht too..."

Enthralled by his confession, Winter didn't notice the arrival of her companions until Mabel let out a painful-sounding sob. "You killed your own kid?!"

Wilhelm dropped to his ghostly knees, desperate to hug her. His waving arms passed through helplessly. "I know you think me evil, but I knew what would happen! The magic affected those children in terrible ways. I had to do it. At least... at least that power gave me the means to end their lives quickly. No one understands a death by magic. The authorities didn't know what to look for."

Dipper rubbed Mabel's back for a few moments, trying to gather his thoughts. "Is that... is that why you were able to blame their deaths on the toxic sludge from the factory?"

"Yes, my boy. I had some government assistance on that front for a while, but yes."

Soos raised his hand awkwardly. "If I hear you right, you said the magic did stuff. You didn't experiment on them, did you?"

He rose with a sigh and tried to restore his stately demeanor. "Dietrich refused, but some of our colleagues lacked his scruples."

"Oh, boy. This portal thing just sucked all around, didn't it?" Mabel sniffled, getting to her feet with Dipper's help. "That still doesn't make what you did cool, but..." She couldn't think up a conclusion, but her frosty hatred wasn't so frosty anymore. Her eyes lit up with a thought. "Hey, you said the Army built it, right? So was the portal thingy a machine?"

Wilhelm grabbed his lapels and sighed. "It was. Why?"

"Then it's gotta be super old. If nobody's watchin' it, what if it breaks?"

"Or what if it's leaking?" Winter added, running with her train of thought. "We feel magic everywhere, Wilhelm. If you know where the portal is, tell us. We may be the only ones that can keep it under control."

"Gott im himmel," he exhaled, eyes wide. "I should have known... the War Depart—I mean, the Department of Defense expended such effort to bury our work. I wouldn't put it past those bastard bureaucrats to let it rot and cause an even bigger disaster."

"Could you not swear, please?" Dipper requested with an awkward chuckle.

"My apologies. Very well. I will give you the address of the station; even if it's gone, some evidence may be left behind. Search the lot at 618 Gopher Road. Please... if you can absolve us of our sins, or at least prevent more from occurring, do it. Maybe then I can rest in peace." With a dignified wave he faded away, once again taking the fog.

"All right!" Soos blurted out, clapping his hands. "Super Mystery Brothers and/or Sisters, we got a clue!"

"Man, you were kinda quiet," Wendy noted with a tiny smile.

"I do not handle tension well, my redheaded friend."

"Eh, I don't either, to be honest."

"I don't think any of us could handle this stuff very well," Dipper said, trying to look as determined as possible. "Forget it. 618 Gopher Road here we—wait, why does that address seem insanely familiar?"

"The Mystery Shack?" Mabel whispered, eyes bulging. "The portal's in... no... No no no no no no if that's where the portal is then—then we've been—did we—does Grunkle Stan know? D-does our family have anything to do with..."

He wanted to calm her so badly, but Dipper's brain was racing just as fast. "N-no way. There's no way he'd know! He's just a con-man! He's just a-" Wendy and Soos' helpless, stunned expressions offered him no comfort. "Say something! Tell us there's nothing wrong!"

Winter turned away from them and stared off toward where the hum had been, mouth slightly open in thought. "Oh," she murmured. "So that's what he wanted to show me."