They tried to fend off the dolphins, pushing against the strong bodies. “Fingal’s still with them,” yelled Ben. “Look, here he comes. He won’t hurt us.”

But the young dolphin began to join in with the jostling. The circle got even tighter.

“We’re going to be crushed!” shouted Zoe.

Suddenly, between the troughs in the waves, Ben could just see another fin cutting through the water toward them.

“There’s a shark out there!” Ben cried.

Now Zoe understood what the pod was doing. “They’re protecting us,” she said. “They’re guarding us from the shark. And Fingal’s helping them.”

Two of the dolphins peeled away from the pod and swam straight for the shark.

There was a tremendous splash as the three huge creatures crashed together.

“What’s happening?” yelled Ben.

“I can’t see,” Zoe yelled back. “They must be ramming it.”

Their dolphin protectors continued to swim around them. Fingal gave them a reassuring nudge with his nose as he passed. Then the two dolphins were back. The pod was suddenly giving urgent chirps and squeaks.

“They must have chased it away,” Ben shouted. “There’s no sign —”

To Zoe’s horror, he cried out and disappeared under the water.

The dolphins dived frantically. Zoe tried to follow, but the life jacket kept her on the surface. She tore at the straps, flung it off, and dived, searching for her brother.

Once she saw him, the blood turned to ice in her veins. The shark had swum under the pod and was biting one of Ben’s flippers, shaking him like a rag doll. Zoe swam down and tried to pull Ben away. But she was no match for the huge shark.

Zoe kicked down hard with her heel and whacked the shark on its nose. The shark recoiled, letting go of the flipper. Zoe grabbed Ben’s life jacket and made for the surface as the shark lunged again.

The shark’s mouth was open wide, showing rows of sharp, deadly teeth. Suddenly, something sleek and gray shot across and rammed the shark hard in the side of its face.

It was Fingal. The shark reeled at the blow.

Ben’s life jacket was pulling him up to the surface. Zoe swam up beside him.

“I didn’t see it coming!” cried Ben.

They peered anxiously into the depths. Dark shapes were flashing back and forth in a desperate frenzy as the other dolphins joined Fingal in attacking the shark.

“We need to get away from here,” said Zoe. “But how?”

A gray streamlined body pushed in between them and leaped into the air.

The figure swam around and came up to them, a happy grin on its scarred face. Their young friend nudged them with his nose. Then he swam around and came up behind them, lifting their arms as he passed. He did it again.

“What’s he doing?” said Ben.

“He wants us to grab his dorsal fin,” said Zoe. “I think he’s going to give us a tow!”

As Fingal went to pass them again, they grasped his back fin, and at once felt his strength and speed as he pulled them through the water.

“I don’t really care where we go,” Ben shouted back, spluttering a little as the foamy waves splashed in his face. “As long as it’s far away from that shark.”

Fingal swam strongly, keeping his fin just above the surface of the water. Zoe’s hand began to feel numb from hanging on for so long, but Fingal seemed tireless. Then a worry began to form in her head.

“He’s only ever lived in a pool,” Zoe said to Ben. “He could be swimming in circles.”

“You’re right,” Ben called back. “But what else can we do? There’s a hungry shark out there somewhere and —” Ben stopped talking and wiped the water from his eyes. “Do you see what I see?”

“What?” Zoe asked, trying to peer ahead. “What is it?”

“Palm trees!” Ben cried.