August, 1986

After making absolutely certain that he was not being followed by Egret or her lackey, Doc still decided against taking the DeLorean out from its hiding spot. He took a cab home instead, repeatedly making sure that he didn't have anyone tailing him—and, thankfully, he did not.

He was concerned, however, as he saw Clara standing outside the front door, wringing her hands in worry. She paused in slight confusion as Doc returned in a cab, but that clearly didn't matter when compared to what was on her mind.

"Emmett—!"

"Clara, I know what happened to Marty!"

She froze, stunned, completely forgetting about her news.

"You do!?"

"He's been sent somewhere in space and time by a renegade scientist; she'll tell me where and when he is—in exchange for my helping her with her time travel device," Doc said.

"…You didn't say 'yes,' did you!?" Clara asked.

"Of course not! Well, not yet, at least," Doc admitted. "I wanted to check something first—did we receive a letter or some form of communication from Marty in the last twelve hours?"

"No," Clara sighed. "I know what you're thinking, Emmett—you're thinking Marty might have found a way to contact you like you were able to contact him when you ended up in 1885. But there hasn't been anything sent here or hidden away here for us to find."

Doc's face fell.

"If he hasn't sent anything, then something must have happened to prevent him from doing so—or he was sent into the future. …Or far across space…" The multiple possibilities—none of them good—were beginning to sink in. "What am I supposed to do…? I can't give that THRUSH scientist the knowledge of time travel, but I can't abandon Marty to his fate, either…"

"Would she really tell you where Marty is, even if you helped her?" Clara asked. "She sounds just like Mad Dog Tannen—completely without honor. If you helped her, you and Marty would be useless to her at the end of it—but you'd know too much."

"You're right," Doc sighed. "She mentioned names I recognized—Dr. Rutter and Prof. Gelardan. THRUSH wanted Rutter's research on antimatter; he was nearly killed in the struggle and vowed never to work again after his narrow escape. Gelardan was even worse off—THRUSH killed him after they thought he would double-cross them with his findings on the wormhole theory. Marty and I would merely be the next in a long list of THRUSH casualties." He frowned. "Maybe there's some way I can bamboozle her—pretend to work on her device and figure out where and when Marty ended up, and leave her with nothing once I find out."

"…According to Marty, that's what you tried to do with those nationalists to get plutonium from them," Clara said, frowning. "That didn't end well for you."

"…He told you about that…?" Doc asked, wincing.

"Yes, because he knew how I felt; in the back of my mind, I have these memories of a timeline where you died—when Mad Dog shot you, before Marty rewrote everything so that you lived. But I still remember sometimes…" She sighed. "Marty told me how he sometimes remembers seeing you die, too. And you're telling me that this woman is also in league with killers? I don't want to see you get shot again, Emmett—and I know I speak for Marty when I say that he doesn't, too."

"Marty would want to be rescued—he would want to come home!" Doc reminded her.

"Not at the cost of your life," Clara returned. "Marty thinks the world of you—how do you think he'd feel, knowing that something happened to you because you were trying to help him? You cannot risk getting involved any further with that buzzard!"

Doc tried to find a counterargument, but he knew he couldn't find one—Clara was right. Marty was always quick to blame himself for any misfortune of his that led to trouble for Doc. Something like this would leave him inconsolable.

Doc now looked away, an expression of despair finding his features.

"Then… there's nothing I can do," he realized. "If I don't know Marty's location in space and time, I can't bring him home. …We've lost him, Clara."

Clara's expression changed immediately.

"No!" she exclaimed. "I didn't mean for you to give up on him! He wouldn't want you to die, it's true, no more than you would want him to die—but if you were the one missing, Marty wouldn't admit defeat, either."

"Clara, it would take a miracle for me to find Marty now!"

"And you are a man who makes miracles happen," Clara reminded him, gently placing a hand on the side of his face. "You invented a way to travel through time, and you're working on a way to travel through space, as well. You will find Marty—I just know it. Just close your eyes and think about everything that's happened. Something will come to you."

Doc wasn't so sure, but he did as she instructed. Nothing came to mind at first, but as he pondered and pondered, he recalled what he had seen at the ravine.

"There was an odd shimmering, just above the ground—it wasn't from the heat," Doc recalled. "And it was right near where I'd found Marty's skateboard—near the ravine. He must've gotten knocked off of it when he fell through time and space, and maybe that shimmering had something to do with it."

"Have you ever seen anything like that before?" Clara asked. This had to have meant something—and she was sure it was the key to finding Marty.

"No, I don't think…" Doc trailed off. "Wait, I did see something like that—decades ago! This was the same time when I was trying to figure out what college to go to! …Come to think of it, it was at the ravine then, too!"

"…And…?" Clara prompted.

"…I was too preoccupied to give it a second glance," Doc admitted, sheepishly. "If I hadn't had so much on my mind, I certainly would've investigated it, but I had plenty to think about as it was. It's like I told you and the boys—I didn't let anything distract me from picking a college, not even when I tripped…" He trailed off again. "I tripped…? That wasn't what happened…"

If the ripple effect could have been seen, Doc would've seen a gigantic ripple being held back from hitting him by a seemingly invisible barrier—the ripple pushing and pushing against the insurmountable obstacle, trying to reach him and properly alter his memories, but instead continuing to be pushed back.

But the ripple effect could not be seen—and so Doc was unaware of its extreme delay, and unaware of the building pressure, still confused by remembering this detail that didn't quite fit in with his memories.

"…Emmett?" Clara asked.

"…There's something very strange going on at that ravine," Doc realized. "And I'm almost certain Marty's disappearance has something to do with it."

"So do I," Clara agreed.

"…I need to get back there," Doc continued. "If that shimmering shows up again, I'll be ready to inspect…"

He trailed off as the McFlys' BMW now pulled up, and Clara gasped.

"…That's what I wanted to tell you, Emmett," she said. "George and Lorraine practically begged to come over and see if you found anything. George has been all over town looking for Marty with no luck, and Lorraine is at her wits' end. I couldn't refuse."

Doc could only stare, blankly, as George and Lorraine got out of the car, staring at Marty's skateboard, and then looking up at Doc with pleading eyes, silently begging him for some sort of news.

June, 1932

A cup of strong coffee was enough to get young Emmett through the night; he was a man on a mission, determined to find some answers to help his friend—his only truly good friend, he realized. Marty certainly was an odd one, too—Emmett had only met him a few times, and yet, Marty had acted as though they'd known each other far longer than that, especially during their argument on the clock tower…

"You care about me, Doc!"

He'd said that with such conviction—and with that funny nickname Marty seemed to enjoy calling him. "Doc." Emmett had just assumed that was a friendly, good-natured jab at his studious nature. He didn't mind, however—not when he'd been called several less-than-flattering things by his detractors in school. A lot of Marty was a mystery, but there was no doubting his genuine concern—something that Emmett knew to be rare, especially after his disastrous relationship with Edna Strickland…

He pushed that thought aside and returned to his reading.

"Let's see…" he murmured. "The amygdala seems to be the affected area, but that isn't the sole area of the brain that deals with memory—just as I thought. Then my hypothesis about different sensory stimuli affecting memories might end up being the right way to go after all! …So, some hassenpfeffer should work for scent and taste—Marty had some last time he was here. For visual, I could show him what's left of the rocket-powered car. And for audio…" Emmett trailed off, glancing at the Walkman that Marty had left for him to listen to. "Who knows, maybe listening to this might actually help him."

He picked up the device, turning it over in his hands. Marty had, after all, said he was welcome to use it.

"So, how exactly does this play music? It's not a record…" he mused aloud, pausing as his thumb hit the eject button. The tape was ejected, and Emmett took it out of the player, taking a closer look at it, reading the printing on it aloud. "'Bon Jovi, Slippery When Wet.' …Oh, and these must be the song titles… Huh. And 'Copyright 1986 …'" Emmett's eyes widened, and he immediately grabbed a magnifying lens to make sure that he hadn't imagined that. "…Great Scott, it really does say that! …Well, obviously, it's a mistake."

That had to be the only explanation—nothing else made sense! Marty even said it was new—naturally, the copyright was really 1932!

He shook his head and placed the tape back in the Walkman, setting it aside once more as he tried to focus again on the books. But, by now, Emmett's curiosity was getting the better of him; based on Marty's earlier enthusiasm, he, clearly, thought a lot of this odd device with its clearly misprinted copyright date. And Emmett was not only curious as to what was it that Marty seemed to enjoy so much about it, but, indeed, as to how this bizarre device worked.

"Let's see…" he mused. "These, obviously, go over the ears, like so. And this button says 'play,' so I can surmise that this will play the music, like so—Great Scott!"

Whatever it was Emmett had been expecting, a wailing electric guitar had decidedly not been it. By reflex, he practically threw the headphones off and onto the desk with the rest of the device, staring at it like a high-strung cat for a good half-minute.

"…Marty likes this noise?" he asked aloud. Gingerly, he picked the headphones up, holding them slightly away from his ear rather than right over his ears, now able to listen to it without wincing.

"…Tommy's got his six-string in hock…"

Emmett patiently listened to the remainder of the album side before turning the device off and sitting there with even more confusion than before.

"Well… it's not terrible… And I guess if Marty likes it, that's what matters," he mused. "But that line about the guitar gives me an idea that might help Marty with his memory loss…"

And as Emmett continued to plan and work through the night, Marty was sound asleep in the guest room, his dreams a disjointed mess of jumbled voices and blurred faces as the fragments of his memory struggled to reassemble themselves—first he was singing "Johnny B. Goode" on a stage, then he was sobbing in a mall parking lot, then he was on a tower rooftop, staring down the barrel of a gun, then he was setting an almanac on fire, and then he was hanging out at an Old West festival…

Marty now blinked as the sun streamed through the windows of the guest room; it was nearly 9 AM, but all he could think about were the events that he had dreamed about.

"…Man, what kind of life have I lived?" he wondered aloud.

The memories were incomplete; he hadn't been able to see the other people in his brief glimpses into his past, but he still had a lot to ponder over.

He got to his feet and headed down to the kitchen, realizing that there was nothing there except a batch of coffee that had obviously been brewed some time ago—and, judging by how Marty had to take a step back from the coffee, it was incredibly strong.

Shaking his head, Marty wandered over to the lab, and, sure enough, Emmett was there, reading another one of the neuroscience books intently; he didn't even look up at first, prompting Marty to clear his throat.

"Oh! Good morning," Emmett said, finally putting the book aside. "How do you feel? Remember anything?"

"Bits and piece of stuff," Marty replied. "But nothing really makes sense still. Headache's gone, though."

"Yeah, that bump looks a lot better," Emmett realized. "Well, that's good—I'm sure you'll remember more as time goes on."

"Yeah…" Marty mused. "How about you? You were up all night, it looks like."

"Me? Oh, I'm fine—this isn't the first time I've done something like this." He got to his feet, heading to the wheeled chalkboard. "But I'm glad you're here—I think I'm on the verge of a breakthrough. Look at this!"

He flipped the chalkboard around, revealing a painstakingly recreated drawing of a cross-section of the human brain, with each different segment of the brain labeled.

"Holy…!" Marty began.

"I apologize for the crudity of this diagram," Emmett said, looking a bit embarrassed again. "I know it's not to scale, and I didn't have time to color-code it…"

"No, no—it's fine! It's great!" Marty insisted, stunned. "Way better than I could ever draw!"

"Well, thanks…" Emmett replied, grabbing a pointer. "Anyway, here are two of the pertinent areas—the hippocampus and the amygdala."

"Hippocampus and amygdala," Marty repeated. "…It's all Greek to me, Emmett."

"It is Greek—hippocampus means 'sea horse' and amygdala means 'almond.' I guess it's because of the shapes—I can kinda see it in both cases… Well, that's not important—what's important is that both of these play a role in memory—the hippocampus is how you remember facts and figures, and forming new memories. Yours seems to be fine—you remember everything that happened since I found you last night, right?"

"Yeah, you tripped over me, and after you calmed down, you brought me here, even sprang for a house call—"

"Okay, great; just as I thought—your hippocampus is working as it should."

"That's good…"

"The amygdala is where the seat of your problem is," Emmett continued. "This is where long-term memories are stored, and a lot of them are tied to your emotions, so all those things that mean a lot to you—all those things you're struggling to recall—are here."

"That tiny thing is the cause of all my problems?" Marty wondered aloud.

"Ironic isn't it?" Emmett sighed. "But you know what I think?"

"What?"

"The fact that this is tied to emotions is probably the key to everything," Emmett theorized. "Think about it—you got hurt, but the physical signs of it are rapidly healing, and yet, you can't remember. I think there's some amount of shock that's involved here—that's probably why people just spontaneously recover from amnesia, once their emotions get another jump-start. That's also why the physician was confident that you'll recover, too."

"But when!?" Marty exclaimed. "This feels like it's gonna last forever—I hate it!"

"Well, your emotions are working fine—that's also a good sign that you're capable of a full recovery," Emmett noted. He sighed, placing a hand on Marty's shoulder. "I know it's not easy, Marty, but I already promised that I'm going to help you through this. I wish I had all the answers for you, and I'm doing my best to find them. It's looking really good for you—your amygdala seems physically fine, so there's no reason why you shouldn't make a full recovery. You just need to hang in there until it happens."

"Right," Marty sighed, knowing he should be grateful for all that Emmett was doing for him. "So, how does my playing the organ last night fit in to everything? Being able to read sheet music and play an instrument aren't new things, but I was able to remember without thinking about them."

"Ah! Well, the answer is elsewhere—part of it is here," Emmett pointed to another part of the brain. "This is the cerebellum, this is involved in motor memory—how you remembered to move your fingers to play the organ. And here is the temporal lobe; it works with the hippocampus and the amygdala to remember things like languages—and reading sheet music is a lot like reading in another language." Emmett glanced back at his diagram and chuckled. "Speaking of language, it's kind of funny."

"What is?" Marty asked.

"How the same word can mean very different things. In this context, 'temporal' refers to the temple region of the head," Emmett mused. "But, in my area—physics—'temporal' refers to time—like space-time."

Marty blinked.

"…Say that again?"

"Space-time. Oh, you know—the fourth dimension? That's an area of physics that absolutely fascinates me—I'm hoping to study it in college."

Marty looked away for a moment and murmured something under his breath.

"Did you say something?" Emmett asked, slightly baffled.

"'You're not thinking fourth-dimensionally.' Someone told me that a couple times," Marty recalled. "Sounded a lot like you, actually."

"Huh. Well, I don't know about that; we didn't get around to discussing the fourth dimension on your other visits, sadly—but if you get your memory back, maybe we can. I'd love to know what you know about it—it's almost an obsession with me, really…" He trailed off, frowning. "It is an obsession—look at me, going on about this when I'm supposed to be helping you!"

"It's fine, Emmett—really; you've done so much already," Marty insisted. "I think it's great that you know what you wanna do with your life."

"Well, right now, let's get back to focusing on your memory," Emmett replied. "The temporal lobe and the cerebellum are how you can still remember to read and play music. …You had guitar picks in your pocket last night; I can assume that you play guitar, right?"

"Sounds about right, yeah," Marty agreed, pulling one from his pocket again as he recalled again the fragment of memory of him singing "Johnny B. Goode" with a guitar in his hands.

"That's what I thought. I want to try a little experiment," Emmett said. He pulled a guitar case from under the desk.

"…That wasn't there last night," Marty realized.

"No, it wasn't; I ran out and got it about an hour ago."

"You what!?" Marty exclaimed. "Jeez, Emmett; you're throwing away all this money just to try to cure my amnesia!?"

"If it ends up helping, I don't consider it a waste," Emmett shrugged. "Anyway, I got a good deal on it—you remember Trixie Trotter?"

"…No, not really."

"…Right. Sorry. Well, take my word on it that she and her husband are friends of ours; I helped her get a job at a nearby music store in town—she was more than willing to give me a discount on this secondhand guitar."

He opened the case.

"Acoustic," Marty commented. "You want me to try playing that?"

"If my hunch is correct, you should be able to," Emmett said. "And even though different parts of the brain are responsible for different aspects of memory, they're still connected—activating one or two should affect the others. Let's just see."

He handed Marty the guitar, who silently held it for a moment before gently strumming it; switching to autopilot almost immediately, he started tuning the strings, and then started to play the acoustic chords of "Wanted Dead or Alive"—the same song he'd been listening to just before losing his memory—and started singing the lyrics.

Emmett's eyes widened—he recognized the song as one of the ones he'd listened to last night when playing around with Marty's Walkman. In spite of not being the one to write the song, Marty had apparently learned the chords and the lyrics by ear—and had learned them well.

You've got a talented brain, Marty, Emmett silently commended. And I'm going to do my best to make sure it gets back to the way it was before all this happened.

Notes: THRUSH, like Dr. Egret herself, are from The Man from U.N.C.L.E.; so is Dr. Rutter; Prof. Gelardan was an OC I did for an MFU fic last year; it's just my way of tying together my fic universe/timeline.

Updates to this fic will be a bit slow from here on out, at least for the next few weeks; I'm taking on a daily writing prompts challenge for June, so my focus will be on that. I do plan to write some BTTF fics for that project, which will be posted on AO3, and I'll continue working on this fic when I can.