"What is it, Amy? You have something?"

She dropped the notebook on the table and riffled through the pages.

"It was here," she mumbled. "Right here."

"What was?" Dan asked.

Amy turned the pages until she came to a map. A notation below indicated that it depicted the world as it was in the fourth century B.C.

"It's not really the right century, but I thought it was interesting and wanted a copy."

Amy stabbed her finger at the coastline of what was now Tunisia, then drew it west past Morocco and across the Strait of Gibraltar. To the north lay the borders of a country they all recognized as Spain.

Just inland from the southwest coast, there was a large region marked with a circle. In that circle was written a single word: Tartessos.

"Ladies and gentlemen," Dan said, breaking the silence. "It looks like we have just discovered Atlantis."

"Awesomesauce!" said Atticus, and pumped his fist.

April May wondered how to bill her clients in a way that really captured the scale of the work she did. Not by the hour or per project, but by the empty two liter of Electroshock Cherry Limeade Caffeine Blast. One gla.s.s consumed meant an amateur job - breaking into a gmail or Facebook account. Breaking into the Cahills' systems had been a three-bottle project and she would charge handsomely for it.

And now here she was sitting in front of her two gleaming monitors, surrounded by six empty bottles. A seventh was in her hand and half empty already.

Finding out what J. Rutherford Pierce was up to was the biggest project of her career. Part of the problem was that before a certain time, there barely was a J. Rutherford Pierce. Oh, he existed, but hardly in the form he was now. He was a second rater, a loser.

How did he become the man he was? And more important, what kind of man is he planning on becoming next?

It had seemed so innocent in the beginning when he hired her to get some dirt on a couple of rich brats. Easy. Harmless. But then she saw the picture. Some thick-necked goon holding the business end of a hypodermic needle to Amy Cahill's neck. Pierce didn't want to embarra.s.s Amy, he wanted to kill her. And probably her friends, too.

April May tried to tell herself it was a mistake. A muscleman who jumped the gun and went in for an unsanctioned kill. It worked for a while as a reasonable theory, but the more April May learned, the more it sounded like something else - wishful thinking. She needed to know for sure. And if a man like Pierce was trying to kill a couple of kids, what was the endgame?

April May put her fingers to the keyboard and soon that delicious feeling of becoming one with the networks washed over her. She avoided all of the obvious places information might be. Pierce's e-mail. His cell phone. He was too smart to store anything important somewhere so obvious. No, anything worthwhile would be on the Founders Media network, hidden away on a remote hub. Since she had built a great deal of the security protocols for Founders, she was going to get past them. It was just a matter of time.

April May slithered through human resources and accounting, then dipped in and out of a few isolated terminals. She searched the hard drive of a reporter in Bogota, Colombia, and the Twitter account of a Founders Media intern in Des Moines, Iowa. April found a few juicy secrets here and there - some even worth filing away for later - but nothing that explained what Pierce was up to.

There was a ping as April moved through the system. She ignored it at first but the sound grew louder each time, and finally she forced herself to break the trance and look over at her second monitor.

There, in pale green letters, were the words: There's a mouse in the maze.

April May almost spilled her Electroshock Cherry Limeade. Interesting.

An old security subroutine had been activated. She had created it to watch for invaders on the network, and it looked like it had just sniffed someone out. April May delved into the system logs. This particular mouse had been poking around for a few days now, but the strange thing was, it hadn't done any damage. No viruses. No downloads of sensitive data. That eliminated blackmail, corporate espionage, and most black hat hackers.

"Who are you?" she asked the little mouse.

April May turned her attention to the second monitor. She tracked the mouse for a few minutes, a funny feeling growing in her stomach. The mouse was very good and very familiar. A few minutes later, and she was positive. She was staring at the Cahills' very own pet hacker.

April May smiled. The mouse was good, nearly as good as she was. She took another slug of soda and inspiration struck. Searching Pierce's systems could take weeks and might not work. But sitting right in front of her was one of the Cahill team. Did the Cahills know why they were targets?

"Stay right there," she said, staring at the screen. "Stay right where you are."

April spent the next hour building elaborate security protocols, all the while keeping an eye on her mouse. Once she was satisfied, she opened the chat interface. She was about to start typing but stopped herself. No reason to miss an opportunity. April May wove a very clever and nearly invisible bit of code into the chat system. The mouse would see nothing but text, but if it responded, she would get a tiny foothold into the new Cahill system. Once she was done, April May cracked her knuckles and set them on the keys.

What do I say?

She felt a strange bundle of nerves in her stomach as she thought of the real live human behind the lights of her system. She paused, then lowered a single finger and typed two words.

Pony sat in front of his computer, staring at two words in glowing type.

Hi there.

He looked behind him, expecting to see Ian or one of the others messing with him, but the command center was empty. Just him, the darkness, and the words. He set his fingers on the keys and then pulled them back again. This was strange. Too strange to not be careful. He moved to his second machine and did some tracing.

"Unbelievable," he whispered. "Un-freaking-believable!"

He had never seen such a complicated routing. And so masterfully done! The signal was coming from outside the command center but it was impossible to tell from where. Whoever was contacting him could be in the house next door or at a cyber cafe in Mumbai.

The really interesting thing, though, was that the routing was almost too complicated. There was no reason to go that overboard unless you were trying to send a message. But what message?

Who do you know that's this good? And to that question there was only one answer. April May.

Pony scrambled for his phone. Someone had to tell him what to do! He called Ian, and then Hamilton and Jonah, but got no response. It's four A.M.! Who goes to bed this early!? He was about to run downstairs, but a thought checked him. What if she was gone when he got back?

Apparently, this one was up to him. Pony checked the communication stream again. Definitely nothing coming through but plain text. April May wasn't sending a virus or anything like that. She only wanted to talk. Pony decided to keep his response simple, too.

Hi.

His reply sat on screen for a moment. He started to think that maybe April May had gotten spooked, but there was another ping.

You know who I am?

Sure, Pony typed. You're the Queen of the Universe.

Flattering, April responded. Wanna fill me in on you?

They call me Pony.

You're not bad.

Pony grinned. He was really doing it! He was talking to the great April May! He was afraid his brain was going to rupture from pure fanboy glee. His fingers shook as he resumed typing.

What can I do for you? Pony typed.

Something's been bothering me lately, April typed. Thought you might have an opinion about it.

Pony frowned.

I won't give you anything that will hurt my friends.

I'm not asking for any, April May replied. I'm just asking a question. Freelance genius to freelance genius.

Pony flushed with pride, but thought a moment before he answered. What do you want to know?

April May stared at the words on the screen, a jolt of nerves in her stomach. She grabbed her bottle of soda and drowned it in caffeine. The ping of an e-mail notification came from her secondary system.

April glanced up. One e-mail stood out from the others, bold and highlighted in red, like it was screaming at her. It was from Pierce, demanding to know where the Cahills were. What they were doing. How he could find them. April took a swig of Electroshock Cherry Limeade Caffeine Blast and began to type.

Who's the bad guy? You? Or me?

"But how can Atlantis be Spain?" Dan asked as the Mediterranean slipped beneath their small plane. "Last time I checked, Spain wasn't even an island!"

Atticus was sitting in the back, wedged between Amy and Jake, his lap full of books. He had been immersed in his research ever since they left the museum. After their chase through the streets of Tunis, there was far too much media and police interest in the Cahills for them to go to the airport, so Jonah's pilot had made a last-minute switch-up. The four kids had rented a boat and met the pilot and his seaplane a mile offsh.o.r.e. It would be another hour still before they landed near the Spanish coast and were picked up by another boat.

"In actuality, it matches up pretty well with what Plato wrote," Atticus said. "Atlantis was supposed to be to the west of the Pillars of Hercules, which we know are the rocks on either side of the Strait of Gibraltar. Spain is definitely west of that. And apparently Plato's not the only one who thinks this is the place. A scientist named Richard Freund has been studying the possibility for years."

"So why haven't we heard about him?" Dan asked.

Atticus shifted in his seat. "Well . . . most people think he's nuts."

"Sounds like our kind of guy."

"But he's found some interesting stuff," Atticus said. "According to him, there used to be a huge bay in southern Spain. He says Atlantis was built right on the water in a series of concentric circles with amazing temples and ports and everything. And what we know about Tartessos definitely matches up with the legend of Atlantis. It was incredibly rich, largely from the ores it mined from the surrounding area. But then, thousands of years ago, a ma.s.sive tsunami swept into that area and would have wrecked the entire city. Over the years, it was covered with dozens of feet of silt. Eventually, the whole thing became a big marshland and Spain made it a national park."

"So does this guy have actual, you know, proof?" Dan asked.

Atticus's voice got high and squeaky. "He has some interesting images on ground-penetrating radar," he said carefully. "And some people agree that some sites look like they could, maybe, be memorials to the lost city. There's something down there all right, but the whole area is too marshy to do a lot of excavating. I don't know! It's why we're checking it out, okay?" Atticus plunged back into his books.

Dan looked around the plane, frowning. He and Amy had flown all around the world, a lot of the time with Atticus and Jake with them. But he'd never known a flight so silent. Amy stared out the plane's window with the same broody silence that had surrounded her since they had left the library.

Dan knew what it was about, but there was nothing he could say. As slick as she'd tried to be, he'd seen her looking in his backpack. He knew what she must have found.

Dan flushed. He couldn't help feeling as if he'd been caught doing something shameful, like stealing or conspiring with the enemy. But they were just some brochures. And he'd told Amy that he was done with the Cahills after they figured out how to stop Pierce. If they figured out how to stop Pierce. He couldn't do this anymore. It felt as if his skin was getting tighter every day, until soon it would suffocate him. Is that what she wanted for him?

The more he thought about it, the more his guilt was replaced with anger. Anger at Amy. He'd been mad at her before - a lot - but it was usually a "hey you borrowed my hoodie without asking" kind of anger. This was real, burning hot, even teary. So much so that he couldn't bring himself to say anything about it. They'd been through so much together and they'd always been able to talk through anything. It was the only way they'd survived. It was impossible, unthinkable, but something had changed.

The pilot announced that he was preparing to land. Dan clipped his seat belt in place and looked out the window, gulping when all he saw below them was the iron sweep of the ocean. Landing without a runway just didn't seem right.

It ended up being surprisingly smooth, though, and minutes later they were met by a fishing boat. They all stepped uneasily onto the plane's pontoons before taking the hand of a grizzled-looking fisherman and crossing over onto the boat deck.

Dan steadied himself against the railing as Jake helped Atticus with his life vest. Amy stood off by herself, again, the hood of her sweatshirt pulled up as she watched the churn of the boat's wake with empty eyes. This is ridiculous! Dan started to cross the deck toward her, but something stopped him.

Once we have the silphium, we'll both be more relaxed, Dan thought. We'll talk then. Dan huddled against the railing, hoping it was true.

A Land Rover met them at the sh.o.r.e and brought them into Donana National Park, which did not look to Dan like the home of the world's most famous sunken city. It was a mix of sand dunes and lush, reedy marshlands. About five miles inland, they moved onto a flat plain of sun-bleached dirt dotted with sprigs of dry reeds and tufts of gra.s.s.

"So, this is Atlantis," Dan said. "Man, the Aquaman comic books were way off."

"You wouldn't look so great, either, if you'd been covered in silt for a few thousand years," Atticus shot back.

A dusty camp came into view. It consisted of a handful of tents with scientists bustling around in khaki and hiking boots. Their Land Rover came to a halt just outside of camp.

"What if we're wrong," Atticus said, looking even younger than usual. "What if Dad's not here and Pierce really does have him?"

Dan looked back at his friend. "Hey, when are you ever wrong? He's here. So, what's the plan? Jake, do you want to -"

Amy threw open her door and started across the plain. Dan and the others exchanged a look.

It's like we're not even here, Dan thought, and then the three of them piled out of the car with Jake in the lead.

"Hey!" Jake called after Amy. "You remember that whole thing about my dad disliking you, right?"

"Yes," said Amy, not even bothering to turn around. "And I also remember you saying that Dan and I should try making a direct appeal. Just hang back and let me talk to him."

Dan could see the tension in Jake's shoulders ahead of him.

"All due respect to your Leader-tude," Jake called, "but he's my dad and you don't exactly seem in the most diplomatic frame of mind right now."

"I'm fine!"

"You're acting like a crazy person!" Jake fired back.

"Dad!" yelled Atticus, and ran past everyone into the camp.

Dr. Rosenbloom had just emerged from one of the tents. Atticus threw his arms around his very startled father, who spun him around.

"What's going on?" Dr. Rosenbloom asked. "Att, what are you doing here? Are you okay?"

"We're fine."

Jake glanced at Amy and then ran over to join Atticus. "We saw your house," Jake said. "We thought something might have happened to you."

Dr. Rosenbloom's expression cleared and he laughed. "Ah, I guess I was in a bit of a hurry. Sorry if it worried you guys. But aren't you supposed to be back in Rome? Did you miss your flight?" Dr. Rosenbloom waved his own question away. "You know what? It doesn't matter! When you guys see what we've found here, your heads are going to explode right off your shoulders. Come on, let me show you!"

Amy stepped forward, and Dan put up a hand to hold her back. "Amy, wait. Let them -"

"Dr. Rosenbloom!" Amy called.

Dr. Rosenbloom turned. His smile evaporated the second he laid eyes on her. The glow that lit his face from the moment he saw his sons disappeared instantly, replaced with something dark and cold.

"Dad -" Atticus began.

"So, you were worried about me?" Dr. Rosenbloom repeated, anger coloring his voice.

"It's true," Jake said. "We -"

Dr. Rosenbloom broke away from them and marched across the field, his eyes locked on Amy.

"Sir, I . . ."