Zoe tugged at their uncle’s sleeve. “Tell us the details!” she said impatiently.

“I want you to look at this,” said Uncle Stephen. He pointed to a huge wall monitor displaying a website for a marine park. The park looked bright and welcoming, with the slogan “Mundo Marino, the jewel of the Caribbean Coast” on top of the webpage.

“We have an operative who keeps track of what goes on in water parks and zoos all over the world,” Uncle Stephen explained.

“Recently, she picked up reports of problems at this place in Mexico,” added Erika. “It used to be run by an old man who loved all forms of marine life.”

Uncle Stephen continued the story. “He died six months ago, so his son took it over,” he said. “He didn’t spend enough money on the park and if any member of staff complained, he fired them. By the time the authorities found out and closed it down, many animals were in terribly unhealthy.”

“That’s horrible!” said Ben.

“It gets worse,” Uncle Stephen said. “Of the four bottlenose dolphins there, only one four-year-old male named Fingal was still alive. And he has a scar running from his right eye to just below his mouth, so he must have been mistreated.”

“That’s awful,” said Zoe. “So we need to rescue Fingal. But if the park was closed down, where is he now?”

“We don’t know,” said Erika. “When the owner found out the authorities were after him, he dumped all the animals in the ocean. Most of the animals were born in captivity and won’t be able to survive in the wild.”

“So he could be anywhere in the Caribbean by now,” said Ben.

“We don’t think he’s gone far,” said Uncle Stephen, “and that’s part of the problem.”

Uncle Stephen tapped a key, bringing a map of the Caribbean Sea to the screen. He indicated a point on the southeast coast of Mexico. “San Miguel,” he said. “That’s where Fingal was dumped four days ago.”

“We’ve been monitoring local radio reports,” Uncle Stephen said, “and it seems that a young dolphin has been harassing fishermen in San Miguel. We think this must be Fingal. He seems to be after their fish.”

“Fingal was born in the park, so he would naturally go to humans for his food,” said Erika.

“The fishermen won’t like that,” said Zoe.

“You’re right,” said Uncle Stephen. “And that’s why your mission is so urgent. Fingal will either get hurt or caught in a net if he’s not rescued soon. And there’s always the danger of a shark attacking a young dolphin that isn’t protected by a pod.”

Erika nodded and added, “Fingal needs rehabilitation before it’ll be safe for him to live in the wild,” she said.

“Who does that kind of rehabilitation?” asked Ben.

“The Agua Clara Dolphin Sanctuary is about 100 miles from there,” said Uncle Stephen, “but they don’t have the time or resources to travel that far to search for a dolphin in trouble.”

A sly grin crawled across their uncle’s face. “However, I can think of one way they would find him very quickly,” he said. “If he were tracked down and encouraged to sit still for a while, then maybe the center could come and get him.”

“Well, Ben,” Zoe said, winking at her twin brother. “I wonder who our uncle has in mind for this challenging task?”

“I suppose we could do it, Zoe,” Ben said with a grin. “We’re not very busy lately, and it is summer vacation.”

Uncle Stephen smiled at them. “I knew my wonderful nephew and niece would be up for it.”

“When do we leave for San Miguel?” asked Zoe eagerly.

“We’ll be leaving as soon as you’ve got all of your equipment,” said Erika. “I’ll pretend to be your aunt who is taking you along on vacation while I work. I’m going to pose as an environmentalist.”

“You are an environmentalist!” Uncle Stephen said with a laugh. He turned to Ben and Zoe. “Her reason for being in a Mexican fishing village is real. I’ve been looking into the problem of dolphins being caught in fishing nets for some time. There are devices that mimic the call of a much larger marine mammal so that dolphins are warned to stay well away.”

“But those devices can be too expensive for poor fishing communities like those around the San Miguel area,” Erika added.

“That’s right,” Uncle Stephen said with a nod. “So I’ve developed my own version that is much cheaper and just as effective.”

“I’m going to offer the fishermen a free trial,” said Erika. “And while I’m doing that, you can search for Fingal.”

“Will we get to do some snorkeling?” Ben asked.

Uncle Stephen rubbed his hands together. “You certainly will,” he said. “And you’ll be using my latest invention to do it.”

He opened a drawer and rummaged through it for a few moments. Finally, he pulled out two snorkels and some flippers, and then handed them to Ben and Zoe.

“Snorkels have already been invented, Uncle Stephen,” Zoe said, smiling.

“These may look like normal snorkels,” said their uncle, “but they’re not. They’re GILS — Great Integrated Life Support. Unlike a snorkel, this will give you ten minutes of oxygen.” Uncle Stephen pointed to Zoe’s device. “See the little capsule there in the mouthpiece? This is a special compressed air tank. All you have to do is go back up to the surface and it refills automatically. I’ve set it to give you a strong taste of peppermint when the air is about to run out so you have a warning. And if you look closely at the mask, you’ll see it’s designed to give improved underwater visibility.”

“And let me guess,” said Ben, pointing at the flippers. “These are no ordinary flippers, either.”

“Indeed,” Uncle Stephen said, smiling. “They’re extra streamlined for increased speed.”

“Cool!” said Ben. He slipped on the flippers and waddled round the room. “They feel really light — and strong.”

“What sort of boat will we be using?” asked Zoe.

“A speedboat?” said Ben hopefully.

“Don’t be silly, Ben,” Zoe said with a laugh. “The engine would frighten Fingal away.”

“Zoe’s right,” said Erika. “I’ll be renting a sailing dinghy for you.”

“Perfect!” Zoe said, pumping her fist in the air.

Ben grinned. “You would say that,” he said.

“I bet right now you’re wishing you’d taken those sailing courses with me last summer,” said Zoe.

Erika opened Uncle Stephen’s drawer. After removing two apple cores and an old milk carton, she produced what looked like two handheld game consoles and held them out to Ben and Zoe. “Of course you can’t go without your BUGs,” she said.

Ben and Zoe’s BUGs were impressive little gadgets. They had built-in radios and phones, satellite trackers, translators, and countless other useful gadgets. They even had one or two video games, which Ben loved.

“Wait a minute,” said Ben. “Are these still going to work in the ocean?”

“They’re waterproof,” said Uncle Stephen. “I’ve tested them in my bathtub!”

Ben and Zoe groaned.

“I’ve also added a limpet,” Uncle Stephen said, ignoring them. “It’s a wireless extension of your BUGs.”

Zoe turned her BUG over in her hand. She peeled off a coin-sized piece of rubber with a metal device embedded in it. “Is this it?” she asked.

“Yep,” said Uncle Stephen. “It’s designed to stick to the side of your boat by giving off a slimy substance, just like a real limpet does. It transmits and identifies calls underwater. All the info will be displayed on your BUG screens.”

“Awesome,” said Zoe.

“You’ll also have a supply of treats to lure Fingal to you,” Erika added.

“I made up the recipe,” Uncle Stephen said. “They’re only tasty to dolphins.”

“Good,” said Zoe. “Otherwise Ben would eat them all!”

Ben smiled. “She’s probably right,” he said with a shrug.

“Time for you to leave,” said Uncle Stephen. “The WILD jet is fueled and ready to go — and Fingal is depending on you.”

“I think there’s something you forgot to tell them, Dr. Fisher,” said Erika.

“What’s that?” Uncle Stephen asked.

“The weather?” Erika said as she raised her left eyebrow.

“Oh yes!” said their uncle. He turned to face Ben and Zoe. “One other thing — it’s hurricane season in the Caribbean.” Uncle Stephen frowned. “I hope that won’t scare you off,” he said.

“No way!” said Zoe. “Fingal, here we come!”