EMMET HAD NO IDEA THAT RAEBURN COULD PILOT AN airboat. But as they zipped through the Everglades, he thought, in his inexpert opinion, she was pretty darned good at it. Maybe as good as Calvin.

“If only we had a way to follow him,” Emmet said when they’d hatched their plan on the patio at Calvin’s house.

“Give me your phone,” she said. He handed it over the table with a curious look on his face. Raeburn stood up from the table and stepped into the yard to make a call. She was back in less than a minute.

“We can borrow an airboat from my cousin if we can get to the dock,” she said.

“Um. You know how to drive an airboat?” he asked.

“Emmet, dude,” she said with a sigh. “I’ve been piloting airboats since I was six.”

Emmet thought a moment.

“Okay, we tell Mrs. Clawson we’re going to the library …” Emmet had to stop a minute to chuckle. Mrs. Clawson was supposed to be watching them as a favor to Dr. Geaux. But she was the worst babysitter ever. “We take the bus to the dock,” he said. “Stuke, you’re not up to a swamp trip yet. Take my phone and stay at the library. If my dad or Dr. Geaux calls, you answer and tell them I’m in the bathroom or something.”

Emmet swallowed hard, just realizing he was making plans for another trip into the Everglades: Land of the Pterogators. This was something he swore he’d never do again. The thought made him sweat a little.

Riley brought supplies in a duffel bag. Bottled water, insect repellent, granola bars, flashlights, and other assorted survival gear.

“How will we avoid the search teams?” Raeburn said.

Emmet held up the portable scanner he’d “borrowed” from the Geaux house.

After Dr. Geaux came to Emmet’s house looking for Calvin, she dropped him off at her house so that Mrs. Clawson could keep an eye on him. It was now almost noon and Calvin had been missing since … Well, no one knew exactly how long, because he’d snuck out of his house sometime in the middle of the night. Sneaky Calvin. He’d gone rogue.

Emmet asked if it was okay if Riley, Raeburn, and Stuke came over to keep him company. They could at least try to do a group project they were working on for school. It would occupy his mind while Calvin was missing. Dr. Geaux agreed, and they waited until the early afternoon to hatch their plot. By then it was clear Calvin was going to be harder to find than anyone expected.

They gathered on the patio and sat around the table.

“How did you pull this off?” Raeburn asked Emmet. Apollo climbed up in her lap and began a campaign to convince her that he was the cutest dog in the world. It appeared to be working. He lay on his back with paws in the air, enjoying a belly rub.

“Parents never complain when you say you don’t want to fall behind on homework. Even though school is closed until they can figure out what to do about the infestation,” Emmet said. “And having you guys around should keep me from worrying about Calvin.”

“You’re getting too good at this,” Riley said, shaking her head.

Emmet wished they could all be up in the tree house — less chance of Mrs. Clawson overhearing them — but she was in the den with the TV turned up so loud that Emmet doubted she would notice if he decided to jackhammer up the tile in the dining room. Besides, Stuke was still in physical therapy for his leg, and wasn’t too confident about climbing yet.

“It required a small amount of deception on my part,” Emmet said. “Which I’ll admit I feel bad about, but I needed you guys here.”

“Did he tell you where he was going?” Riley asked, after a pause.

“No,” Emmet said. “And we will have a long discussion on that very topic once I get my hands on him.”

Raeburn cocked her head, looking at him quizzically.

“What?” Emmet asked.

“You really don’t know where he is?” she asked seriously. Emmet didn’t like the searching look she was giving him. Leave it to a girl to make you feel like you’re under a microscope. He honestly didn’t know anything, but she was still making him feel guilty. How did girls do that?

“No, honestly,” he said. “This is all Calvin’s deal, which is why it’s so upsetting. I’m the reckless one. Unless he’s being attacked by a horde of Blood Jackets, or about to be eaten by a Muraecuda, he’s not exactly … The word escapes me,” Emmet said.

Stuke looked up from his homework. “Proactive?” He waved to his vocab list. Only Stuke was actually concentrating on schoolwork.

“Exactly. Proactive. And I think it has to be connected to Dr. Catalyst somehow,” Emmet said.

“What makes you say that?” Riley asked.

“Process of elimination. Up until now, Calvin has only responded to the situation in front of him. He takes whatever action is required at the time. But after spotting Dr. Crazylyst inside the school, he disappears? There has to be a connection,” Emmet said.

“And what is it?” Raeburn asked.

Emmet slumped back in his chair. “I don’t know. Calvin is so private. He barely talks at all. He’s not exactly …”

“Effusive?” Stuke said, pointing to the vocab list.

“What does that mean?” Emmet asked.

“Gushing and talkative,” Stuke answered proudly.

“That’s the opposite of Calvin, all right,” Emmet said. “You guys have known him a lot longer than me. Where would he go?”

They grew quiet as they thought, but no one seemed to have an answer.

“Hang on here a minute,” Emmet said. “I’ll be right back.”

Emmet walked into the house, past Mrs. Clawson in the den — who completely ignored him — and down the hall to Calvin’s bedroom. He walked in and sat down on the end of the bed, scanning carefully around. Like everything else about Calvin, his personal space was neat and precise. Emmet almost grimaced. It wasn’t normal for a twelve-year-old boy to have a room this clean. There should be dirty underwear everywhere and it should smell like moldy sweat socks, like Emmet’s room did. It reminded him of Calvin’s boat. Everything was sparkling and neatly tucked away.

There was a Florida State Seminoles football poster on the wall. A framed poster on the opposite wall showed the biggest gator Emmet had ever seen, swimming in some canal with a deer in its mouth. A whole deer! It seemed like a very poor choice for a bedroom poster to Emmet.

“That’s just wrong,” he muttered. “Why constantly remind yourself of something that could eat you and lives right outside your window?”

The desk was empty except for a lamp and Calvin’s phone. Dr. Geaux had told him there were no calls or recent text messages in the log. On the wall just above the desk hung a photograph of what must have been his father and Calvin as a young boy. They were in an airboat, zipping along the water in the Everglades. Calvin had a look of pure, unadulterated joy on his face. Looking at the picture made Emmet a little sad. He’d never seen Calvin smile like that.

Emmet lifted the picture off the wall and studied it closely. Calvin was like a smaller version of his dad. He must have been five or six years old when it was taken, and since then his features had changed a little. Emmet thought his friend actually looked more like his mom now. But back then, he had been a miniature Lucas Geaux. But there was something else familiar about the man’s face.

Emmet was pretty sure he’d seen it in the hallway of Tasker Middle School the other night.

Older, a little more wrinkled, and the hair was not as long or dark. But it was the same face he’d seen the night they were attacked by the Blood Jackets.

He left the room, hurrying back to the patio. Emmet sat the picture frame down in the middle of the table. Stuke, Riley, and Raeburn all looked at it with interested eyes.

“Does that guy look familiar?” he asked.

Raeburn and Riley both shook their heads.

“No,” Riley said.

“Look closer,” Emmet prodded.

“What are we looking at?” Riley asked.

“You don’t think that’s the same guy we saw in the school the other night?” Emmet asked.

“No way,” Raeburn said, before Riley could answer. Stuke, of course, had missed the excitement, a point that made Emmet bitter.

“Why ‘no way’?” Emmet asked.

“One, that’s Calvin’s dad, Lucas Geaux,” Raeburn said. “He’s dead. And two, that’s Calvin’s dad, Lucas Geaux. There’s no way he’d be Dr. Catalyst.”

“Why?” Emmet was generally curious.

“You’ve got to understand something,” she said. “When Calvin’s dad died, it was kind of a big deal on the rez. Lucas Geaux is still a legend in the River of Grass.”

“Legend for what?”

Riley and Stuke were sitting in their chairs, watching the conversation between Emmet and Raeburn flow like a tennis match.

“For … everything! In the tribe he’s — well, let’s just say he’s revered. He wasn’t officially involved in tribal politics as a leader or anything, but he knew more about the Everglades than anyone alive. Probably before or since. He was a guide, a hunter, a fierce protector of tribal lands and rights. He could make an airboat sit up and dance, and he — there’s just no way he’s Dr. Catalyst. Besides, he died in a crash.”

“Dr. Catalyst faked his death in a crash, and he’s alive,” Emmet said. “And Dr. Geaux told me Lucas’s body was never found.”

“I know, but it’s not him,” Raeburn said. “Trust me. Somebody dies in an accident out in the Glades — they don’t find the bodies. The gators, every critter with teeth finishes ’em off if they don’t sink into the swamp. Besides the guy we saw was older than Calvin’s dad would be. On top of that, he would never leave his family. He died, Emmet. You need to look elsewhere.”

“You said he could ‘make an airboat sit up and dance.’ Well, Dr. Catalyst used an airboat to fake his death, too! You don’t find that a little convenient?”

“It’s a coincidence. Do you know how many airboats crash in the Glades every year? How many fatalities? They don’t publicize it, because it hurts tourism, but there are a lot of accidents. Besides, Lucas Geaux would never leave his family willingly.”

“Why?”

“It’s just not done. In the Seminole culture, family is the center of everything.”

“Dr. Geaux also told me that him marrying outside the tribe was not well received by his family,” Emmet said.

“I don’t know about that. I just know people still talk about him, and he loved the Everglades, and —”

“Exactly,” Emmet interrupted. “That makes him the perfect Dr. Catalyst.”

“Except you’re forgetting something,” Raeburn said.

“What?”

“Think.” She smiled at him, but Emmet was stumped. Riley picked up the picture and studied it for a moment.

“I think Raeburn is right,” she said. “The guy in the hallway looked older to me. The math doesn’t work. This guy is in his early thirties. If Calvin was five or six when this was taken, his dad would be like forty now. The guy we saw was in his fifties, at least. Maybe older.”

Emmet slumped back in the chair and looked at Raeburn.

“And if Calvin’s dad is still alive,” he said, “he probably doesn’t have the scientific knowledge to create hybrid species.”

Raeburn smiled and nodded.

“I still think there’s a connection somehow,” Emmet said. “Calvin went to find it.”

“So let’s go find him,” Raeburn said.

And that’s how they came to be rushing through the swamp looking for Calvin, with only a couple of hours before they had to get back. Stuke waited dutifully at the library with Emmet’s cell phone. Emmet had taken Calvin’s off the desk. Raeburn knew Lucas Geaux’s old camp was up in the Shark River Slough, near the mouth of the Broad River, and that’s where they headed. It wasn’t being searched yet, and was as good a place as any to start looking.

Everything was going fine until the boat broke down.