Author's Note:

I can't believe that I'm on Book 2 of The Volcano Sisters Saga. In Between Boundaries, we finally learn that Sierra is a volcano sister and that she has been hiding a secret so long from Trevor but now, she has come out in the open to reveal it.

Anyways…Here's Going Under!

Enjoy :3

Disclaimer: I don't own Journey To The Center Of The Earth. It belongs to New Line Cinemas and Walden Media but I do own my OCs.

5:45 PM

Sierra was asleep on the couch, magma illuminating through her veins.

Trevor was looking at the picture of him, Layla and 5 year old Sierra.

He couldn't believe how much the young girl has grown.

Trevor knew that he wasn't going to lose his little girl to some volcanic conspiracy.

As he was watching Sierra sleep, he could see a red blinking light that was constantly blinking on and off.

Trevor saw the number 4 being displayed in the message number circle.

4 new messages. Huh…I wonder who they're from… He said to himself as he pressed the receive button.

Just when he did that, the speaker made a loud beeping sound and after it made the beeping sound for about 2 and a half minutes, a voice came on.

It was a shy voice.

"Trevor, it's me Elizabeth. We are on I-95 and we're heading your way. Sean, say hi to your cousin, Sierra." Elizabeth said as she was driving.

"Hi, Sierra. Just wanted to let you know that we are on our way. I can't wait to see you!" Sean said, excitedly.

Trevor smiled.

He couldn't believe how much the young boy was growing up.

The first time they went on an adventure to the center of the earth, Sean was a little bit stubborn until he met Hannah. When he found out that his Dad died, he turned to Trevor for help. Trevor hugged Sean and protected him.

At the end of the journey, Trevor realized that Sean was turning out to be just like Max.

Trevor now turned to look at the calendar and saw on today's date June the 19th, the word circled in red permanent marker…

SEAN.

He had a lot to do before Sean and Elizabeth arrived.

Trevor looked over at Sierra, who was beginning to wake up from her little nap.

"Hey, Daddy. Who were you on the phone with?" Sierra asked as she began to rub her tired eyes.

Trevor looked back at the answering machine.

"That was your Aunt Elizabeth. She's bringing Sean over to see you for three weeks." He said, looking back at Sierra.

Sierra nodded.

"Okay, Daddy. That sounds great." She said, sleepily as she began to lay back against the couch.

Trevor smiled and then looked back at the mess that was scattered about in the living room.

He had a lot of cleaning up to do before Elizabeth arrived with Sean.

There were empty Chinese food cartons to be thrown away, books and scattered papers to be put away and organized.

Trevor then looked at the answering machine that the number 1 displayed.

It blinked twice.

"I'm not at home. Leave a message." Said the voice of him.

The answering machine beeped.

"Trevor, we are pulling up into your driveway now." Elizabeth's voice said as the number went from 1 to 0.

Trevor looked out the door window and saw Elizabeth's car pulling up.

He then focused on the stuff that was in desperation of being put away.

"Oh no." Trevor said as he was now beginning to work quickly.

6:00 PM

After about a few minutes, Elizabeth arrived at the door with 17 year old Sean.

She smiled at him, reassuringly as Trevor had now gotten done with putting everything away.

He sighed in relief.

Elizabeth knocked on the door.

"Trevor, are you and Sierra in there?" She asked, hoping Trevor could hear her.

Trevor looked at Sierra, who was steadily sleeping.

He smiled at her and then went to go answer the door.

Elizabeth and Sean saw Trevor coming over to the door.

They took a step back and let Trevor open the door.

"Hey, Liz and Sean." Trevor said, in greeting.

Elizabeth crossed her arms.

Sean looked up at him.

"Hi, Uncle Trevor. I'm so glad to see you. You would not believe the last adventure that I have been through. Me and my stepdad, Hank…We went to this Mysterious Island and found my great grandfather Alexander Anderson. You should have been there, Uncle Trevor." He said, his eyes glimmering.

Trevor sighed.

"I know I should have been there, Sean but, there's something wrong with Sierra." He said as he looked at the window in the living room and saw Sierra, lying motionless on the couch.

Elizabeth looked at Sean and thought of an idea.

"Sean, why don't you go inside and spend some time with your cousin?" She said, giving the young man a suggestion.

Sean nodded and began to head in.

"Just let yourself in." Trevor said, reassuringly, before looking back at Elizabeth.

Sean gave Trevor a thumbs up and went in.

"He'll be fine." Trevor said, with a small smile.

He was afraid that Sean was going to be scared of what Sierra was.

"It'll be good for him to see Sierra. How long has it been since he has last seen her?" Elizabeth said as the two were standing there, talking and catching up on things.

"About 5 or 6 years." Trevor said, remembering.

Elizabeth nodded.

"You're right, Trevor. Ooh ooh ooh ooh ooh…" She began to say, remembering something that she had in her car to give to Sierra.

"What is it?" Trevor asked, in wonder.

Elizabeth looked at the car and then looked back at him.

"Stay here. I have something that I need you to give to your daughter." She said, before she went over to the car.

Trevor nodded and watched her walk away.

What did she want to give to Sierra?

….

Sean walked into the house.

He saw the five jars of coins.

Yet again, Sean wasn't impressed but was intrigued.

He must be planning another world trip. Maybe to Hawaii or Fuji. I hope one of those places. Though, still…I'm here to see Sierra. I haven't seen her since she was about eight or nine years old. I hope she's okay. Uncle Trevor said that there was something wrong with her…Hopefully, I can make her feel better. Sean said to himself as he now went into the living room.

When he went into the living room, he saw that Sierra was gone.

She…She was right there on the couch. Where did she go off to? I hope she's okay… Sean said to himself as he looked around the living room.

He then began to look at the door.

"Uncle…Uncle Trevor?!" Sean called out, worriedly.

….

Trevor stood there, patiently with his arms crossed as Elizabeth opened the trunk of her car and took out a wrapped up gift.

It was wrapped in black and red wrapping paper, topped with an orange bow.

Once she got it out, she shut the trunk door and walked over to Trevor.

As Trevor was standing there, he heard Sean calling out for him.

He looked back towards the front door of his house and saw Sean opening the door and coming out.

Elizabeth saw Sean coming out of the house, panting.

"Uncle…Uncle Trevor?" Sean said, running over to them.

Trevor looked from the gift that Elizabeth was holding to Sean.

"Sean, what's wrong?" He asked, looking at the worried teen.

Sean breathed in and out, calmly.

"Sierra…She's…She's gone!" He said, concerned.

Elizabeth looked at him, concerned.

"What do you mean she's gone, dear?" She asked, looking into his eyes.

Trevor nodded at him to continue.

Sean began to calm himself down again.

"She was in the living room, laying down on the couch as we were standing out here but, when I went in, she disappeared." He said, internally panicking.

Sean had tears in his eyes.

Trevor began to hug him for a few minutes.

Sean began to calm down.

He knew that Sierra was around the house but…

Where was she?

"Sean, try looking for Sierra around the kitchen and living room. I'm for certain that she left a magma trail somewhere in there." Trevor said, looking back at the house.

Sean nodded but then looked at him, confused.

"Mag…Magma?" He said, with an eyebrow raised.

Elizabeth had the same expression on her face.

Trevor sighed.

"I'll explain later." He said as Sean began to go back towards the house.

Just as soon as Sean went in, Trevor looked back at Elizabeth, with an awkward look on his face.

"So…What's with the wrapped gift?" He said, changing the subject.

He did not want Elizabeth knowing about what Sierra was.

Sean was just now beginning to find out about her.

Elizabeth looked at the gift and then back up at Trevor.

"This is for Sierra. A friend of Max's studied some sort of volcanic conspiracy and wrote his findings in this book." She said as she gave the gift to Trevor.

Trevor looked at the gift and then back up at her.

"Thank you. I'll make sure that Sierra gets it." He said, thinking of how happy his little girl would be about hearing from one of her uncle's friends.

Elizabeth smiled at him before she went to her car.

"I know that this was rather quick but Sean's stepfather and I are going to be going to Hawaii so…I'm going to need you to watch Sean for ten days." She said as Trevor helped her into her car.

Trevor nodded and was now standing on the other side of the car.

"Ten days…No problem!" He said, in a can-do attitude.

Elizabeth smiled at him.

"Well, I know you can do it. I'll see you when I get back. I have to meet up with Hank at the airport." She said as she started her car and began to drive away.

Trevor smiled and watched as she drove away.

After Elizabeth was gone, Trevor looked back at the house and sighed.

Could he explain to Sean what was going on with Sierra…?

(So…17 year old Sean gets to see his cousin Sierra and his Uncle Trevor for three weeks. Elizabeth, on the other hand is excited because she gets to go on vacation with Sean's stepfather Hank Parsons. Anyways…Stay tuned for chapter two!)