Xavier wasn't lost. He knew exactly where the street he was walking down was, in relation to his mother's childhood home. He just didn't know where it was in relation to Baljeet's childhood home. The map was no help. The more he tried to figure out what all the lines and rectangles meant, the more confused he got.

"Look! There's one of them right over there!"

Xavier jumped. That was his mom! Did he really have permission to... Oh wait. It was okay, it wasn't really his mom. It was just her hyperactive teenage self, with an eerily young version of his grandma.

He turned and waved. "Hi, mom!"

"Huh?" said his mom, glancing in his direction. "Did you say something?" Then she turned to Xavier's grandma. "Mom! Mom, look! It's Jeremy and me's future son Xavier!"

Xavier gulped and inspected his hands to make sure he wasn't fading from existence. That was his dad's name! Someone must have told her! They should have brought a memory erasing device. Fred had one of those.

"Candace," began Xavier's grandma.

A marching band came down the street, drowning her out.

Xavier's mom started talking, but Xavier couldn't hear her either. Once the strains of some archaic marching song had faded, she started to talk again, just as a passing car leaned on its horn.

"Excuse me," said Xavier politely, when his ears had stopped ringing. "Do you know where Baljeet's house is?" He didn't want to mention that he was her grandson. They'd done enough damage already.

He didn't want to disappear.

His mom turned to him angrily and said something, but he couldn't hear because his tinnitus was having a flareup. It subsided to its normal level as quickly as it had risen, and he tried to ask her what she'd said. But when he took a breath to speak, he inhaled a bug and had a coughing fit instead.

"Are you okay?" said his grandma.

Xavier nodded, and said "My brother lent a tool to Baljeet, and we really need it back."

His grandma gave him directions while his mom opened and closed her mouth like she was trying to talk.

"Thanks... uh, Mrs Flynn-Fletcher," said Xavier. He was beginning to get the hang of this time travel stuff.

.

Alicia was having trouble hearing her dad over the whine of the drill, but that was okay. He was showing them his building techniques. He'd said he wasn't as good at it as uncle Ferb, but he was obviously just being modest. They were both really, really good at building stuff, even in the past. She almost wanted to take notes, and she hated taking notes.

Fred really was taking notes. He was being someone who didn't hate doing that as much as Alicia, but who was still very interested in what her dad was doing. She didn't know who. Sometimes, when Fred acted like a stranger, it was almost like he was acting like himself.

Hal leaned into the couch, completely focused on the game he was playing on his Evv. Uncle Perry's fight with his grandpa had got boring in record time.

He had to concentrate as hard as he could, because he was playing the game with his brain. Mind games were his favourite because he didn't even have to move his hands, but they were a bit hard to control. Mental input systems were still really new.

That gave him an idea. And having an idea messed up his focus and slid the little ball on the screen into a chasm. He paused and said "Hey Alton, do you think in twenty years our technology will look as outdated as the technology in the past?"

"Huh?" said Alton. He glanced over at him. "What are you... Are you playing a game?"

He sounded incredulous. Hal was incredulous that he was incredulous. "What? I'm bored!"

"Bored?" Alton repeated. "Did you see how uncle Perry escaped? It was..." He closed his eyes for a second, apparently lost for words. "It was so cool!"

Hal tried to remember. Uncle Perry wasn't in the cage with them anymore. So he must have escaped somehow. But he had no idea how. "He teleported?"

Alton snorted, and looked back out of the cage.

Whatever. It wasn't Hal's fault that his brother was so easily amused. He restarted the game - he had to use the keyboard for that - and took another shot at the Golden Socket.

There was an explosion, and Hal's grandpa yelled "Curse you, Perry the Platypus!"

Hal hunched his shoulders and renewed his focus on the game. He knew the end of a battle when he heard one. He'd have to get off the couch soon. He'd have to stop playing.

.

Xavier had finally worked it out. He'd finally found Baljeet's house. It was a big boring box, like all the other houses in the past. Nervously, he rang the doorbell.

The door was opened by a nervous-looking Indian boy who Xavier recognised from old photo albums. "Yes?"

"Are you Baljeet?" said Xavier. People still said things like that in the past, didn't they? He hoped they did.

The boy looked at him strangely. "Yes...?"

"Fred needs his fwooshawizzledoo back," said Xavier. He could just barely see into the house. There were lots of of straight lines on the inside too. It looked really retro.

"Uh... I think you have got the wrong Baljeet," said the boy slowly.

Xavier's shoulders sagged. "Aren't you... Aren't you uncle Phineas's friend?" He'd been so sure he'd got the right address.

"Uncle Phineas?" said Baljeet, in a confused voice.

That was right. Uncle Phineas didn't have a nephew yet. He didn't even have a niece. "I'm from the future. We need the tool that fuses wood to metal back, or it could mess up time."

That seemed to be the right thing to say. "Oh! Why did you not say so?" Baljeet reached into his pocket and took out the fwooshawizzledoo. "Here!"

"Thanks," said Xavier. "Uh... You didn't show it to the... uh, to Buford, did you?" Yes, Buford. That was his real name. He thought.

"Buford?" repeated Baljeet. "Of course not!"

Xavier breathed a sigh of relief. The professor hadn't seen it. The future was safe, at least from anachronistic fwooshawizzledoos.

.

Hal was wedged so far into the corner of the jet that he couldn't see outside. All he could see was the flooring. It was plastic, with those little raised up grippy things plastic floors always had. He amused himself for a while by inspecting it.

Uncle Perry seemed really mad, for some reason. So did Alton. Neither of them were talking to Hal.

He'd just wanted to see a real mission...

"Sorry about all this," said Alton to uncle Perry. The engine was a lot quieter this time, but uncle Perry still must not have heard, because he didn't reply.

The jet slowed, and the plastic grippy floor retracted with a woosh, dropping Hal and Alton two feet to the sidewalk. As Hal sat there wondering when his muscles would let him stand up, the jet roared away into the sky.

As soon as it was gone, Xavier came down the street.

"Hi, guys," he said. "What are you doing here?"

Hal forgot that he was upset and said "We went on a mission with uncle Perry and Grandpa captured us in a cage, and uncle Perry beat him up and saved us!" It was a shame the beating up part had been so boring.

"Cool," said Xavier, with as much enthusiasm as he ever showed.

"Did you get the fw... The tool back?" Alton asked.

Xavier took the fwooshawizzledoo out of his pocket and grinned.

"Then we better get back," said Alton. He and Xavier began to walk off, strangely confidently.

Hal managed to stand, and ran to catch up. "Wait! How do you know the way?"

Alton rolled his eyes. "Dad's old house is just over there."

It was. The big, disintegrating pile of steel girders in the backyard was new, but it did have that big tree. He remembered the big tree.

They entered through the old-fashioned, manual gate, to see Alicia, Fred, Hal's dad and uncle Phineas were standing around the pile, with uncle Perry already lying at their feet. He was fast.

"Hey," said Alton. "What happened?"

"Well..." said uncle Phineas, "we were gonna build a futuristic undersea palace, but I guess Alicia couldn't hear us over the drill, and... it kinda fell apart."

"Um..." said Hal, but Alton hit him with a crutch before he could elaborate on his theories about the effects of the Parent-Ignorinator.

There was a loud noise, and something began materialising in the backyard. It was a big, egg-shaped thing. In fact, it looked a lot like...

"Whoa!" said uncle Phineas. "Twice in one day! What are the odds?"

The other time machine was completely stationary, yet it also seemed to be approaching from a huge distance. Hal knew why that was - he'd designed their time machine to do the same thing - but it was still fascinating to watch.

The other time machine settled on the lawn next to theirs, and the door opened, revealing... Oh no. It was their parents. Uncle Phineas was smiling, aunt Candace was frowning, and Hal's dad had the same blank expression he always had.

"Dad!" said Alton and Hal, almost in unison. Even if they were in trouble, and Hal thought they probably were, getting to see their dad was a big deal.

"Look, Ferb!" said the younger Uncle Phineas. "It's the future versions of us!"

Alicia ran up to the normal version of her dad and said "Dad, guess what? Guess what? We're back in time! Look!"

Normal uncle Phineas picked her up, laughing. "You sure are!"

Aunt Candace frowned even hard. "Phineas, we're not here to congratulate them."

"You're not?" said kid uncle Phineas. He frowned too.

Hal had known it. They weren't supposed to travel in time. But that wasn't fair. Nobody had ever told him not to. Besides, his mom wasn't there, and his dad couldn't punish him.

His dad could tell his mom, though.

"I told you I'd bust you," said normal aunt Candace, smiling a little.

Xavier looked confused. "You did?"

"You weren't there!" Alicia told him. "You were out looking for Baljeet!"

"And why were you looking for Baljeet?" said aunt Candace, in her slightly scary voice.

Xavier stared at the ground and mumbled for a few seconds, before coming up with "Last time they-" he indicated the younger uncle Phineas and Hal's dad "-came to the future, Fred gave them his fwooshawizzledoo and Alicia thinks it would mess up the future, so we came to get it back." He wrung his hands.

"It was my idea, aunt Candace!" declared Alicia.

She could safely take the blame for most things. She never got punished for doing something if she knew she wasn't supposed to do that. Her parents were fair.

"You're not really gonna punish them, are you?" kid uncle Phineas burst out. "It was an awesome idea! I wish I'd thought of something like that! If I were you, I'd be proud to have a daughter like that!"

Normal uncle Phineas grinned, put Alicia down, and patted his younger self on the shoulder. "Good thing I am you! Of course I'm proud of Alicia. We're all proud of our kids!"

All of them? Did all of them include Hal's dad?

"Except when they mess up the timeline," said aunt Candace severely.

"And that's why we're so glad you came back here!" said normal uncle Phineas.

"Wait, what?" said aunt Candace.

Alton yawned. "I'm with aunt Candace. I only came with you guys so you wouldn't do something really stupid. And you know what Hal did?"

Their dad blinked once.

"He..." began Alton. He looked at uncle Perry, who seemed to be sleeping. "He, uh... I can't tell you until we get home. But it was really, really stupid!"

"It wasn't stupid, it was fun," Hal protested. And boring in some places. But mostly fun.

"I get it!" said young Phineas suddenly, and Hal jumped. Exposing uncle Perry's secret now would mess up the timeline even more telling his grandpa about the sports scores. "You guys remember this!"

"That's right!" said normal uncle Phineas. "If our kids never went back, this would never have happened, and there'd be a time paradox!"

Alicia looked up at him. "What kind of time paradox?" she said anxiously.

Normal uncle Phineas stepped aside. "Ferb?"

Hal's dad said "It would cause a localised time ripple with focuses located at this spot, and the spot from which the time machine was launched. This ripple would be felt from here to approximately halfway to the galactic core, but the effects would be most severely felt within our solar system. Planets may rotate backwards, famous historical figures may appear at the corner store, and bathing may make you more smelly."

"Really?" said aunt Candace. "Huh. That doesn't sound so bad."

"There would also have been a one in three chance one of the focuses would become a supermassive black hole," added Hal's dad.

"And you didn't tell me this?"Aunt Candace demanded, her voice getting higher and higher.

Normal uncle Phineas shrugged. "We thought it was obvious."

"Does that mean we're not in trouble?" said Hal hopefully. Sometimes his mom took away his Evv.

"Ask your mother," said his dad.

Alton groaned.

Normal uncle Phineas smiled. "Don't worry, Alicia, you're not in trouble."

Alicia smiled too.

"You sure are," said aunt Candace, glaring at Xavier and Fred.

Xavier gulped, and Fred blinked and looked at the ground. Hal couldn't figure out who Fred was being. He wasn't talking. It would really help if he talked.

"But since you did save the world or something, I guess you're only grounded for a couple days," Candace added.

Xavier smiled in relief. He'd obviously expected something much worse.

Fred blinked again.

"Okay, time to go home!" normal uncle Phineas announced. "Say goodbye to us!"

They all said goodbye. Alton added "Bye uncle Perry."

Kid uncle Phineas waved. "Bye, guys! See you later!"

Normal uncle Phineas packed the kids time machine into a little cube, and they all got inside the one the parents had arrived in. It had a very roomy interior, much more than in the one the kids had made, and Hal wondered how his dad had done it.

Uncle Phineas pressed a button. A flash later, they were home.