THE HARDEST THING about fitting in at Pizza Night, Nim decided, was acting as if the biggest problem in her life was getting a piece with pepperoni when she wanted anchovies (because at least anchovies were fish and tasted a bit like home).

‘It’s like swimming with a new pod of dolphins,’ she told Ben and Erin, when they took their pizzas out to the deck to sit alone.

‘I wish I could do that!’ Ben exclaimed.

‘I wish we could go to your island,’ Erin said.

‘I wish you could, too,’ said Nim. Saying it made her feel hot inside, as if she were betraying Jack – but it was true. She used to wonder what it would be like to have friends that could talk. Now she’d found out, and she liked it. Nim wanted to be back on her island more than anything else, but she didn’t want to lose Erin and Ben.

She told them what the Professor had said.

‘Jail!’ repeated Erin.

‘But he’s the bad guy!’ Ben said fiercely.

‘He says he’s allowed to catch the animals, because of this Foundation. He says that’s the law, because catching them educates people and protects other animals all around the world.’

‘And he is a Professor,’ said Erin.

‘And I am a stowaway,’ said Nim.

‘But he’s still bad,’ said Ben.

‘We should ask Mum and Dad,’ said Erin.

‘No!’ shouted Nim. ‘He said he’d send me to the Captain if I ever told anyone. I shouldn’t even have told you – and if you help me you’ll get into trouble too!’

‘We don’t care,’ Ben said.

‘All that matters,’ Erin agreed, ‘is keeping you safe and getting Selkie free. So we just have to stick to our plan.’

‘But the best thing we can do right now,’ said Ben, ‘is try to look like we’re having a good time. Let’s get some more pizza!’

Fred rubbed his spiny back against Ben’s leg. Fred had mozzarella strings tangled from his grinning mouth to his claws. He liked pizza, and he liked Ben more and more.

NIM FELT LONELY, climbing back up into her lifeboat with Fred while Erin and Ben stood watch outside their cabin door.

It felt lonely, and when she’d pulled the cover over, it felt dark – black as the deepest sea.

Then she heard a knock – the three quick knocks and two slow that were their signal – then the rocking of someone climbing the struts.

Ben stuck his head in to hand her a torch.

Nim turned it on, and saw why Erin had looked as if she was going to burst with her own secret when she’d said, ‘Sleep tight, Nim!’

The boat had been turned into a bedroom. There were two blankets to sleep on, two towels for covers, a pillow for her and one for Fred, a bottle of water and a banana.

But best of all was remembering the look on Erin and Ben’s faces when she’d shown them the key to Selkie’s prison. They’d touched it as if it were magic – and even though Nim wasn’t a magician, just knowing it was in her pocket made her almost as powerful.

IT WAS SO early the sun wasn’t up when Erin rapped three ‘wake up!’ knocks on the metal strut.

Still half asleep, Nim dropped her pillows and blankets over the side to Erin, just in case a Troppo Tourist used the boat during the day. Then she swung down to the deck, with Fred following. The cool morning air woke them quickly. While Erin tiptoed back into her cabin to hide the bedding, Nim and Fred raced down to the Animal Room. When there was no one around to step on him, Fred liked walking.

With a quick check that no one was watching, Nim unlocked the door and they slipped inside.

‘Hurry!’ she whispered to Selkie as she undid the cage. She felt sorry for the others, but she couldn’t help them yet.

Selkie galumphed down the hall after her and into the elevator, honking with surprise when it went up. Fred grinned a little wider, as if he’d been doing this since he was hatched.

It was dark and deserted as they came out onto the Sea Lion Deck. They raced to the Waterslide Pool and dived into the clear water.

Selkie snorted and rolled, dived and leapt, around and around the pool as fast as she could. Fred sank to the bottom and came up again, sneezing with disgust because he couldn’t find any seaweed.

Nim swam with Selkie and dived with Fred; she couldn’t swim as fast as a sea lion or hold her breath as long as a marine iguana, but she liked trying. She didn’t know exactly how they were going to escape, but she did know they’d all need to be as strong, as fast, and as good at everything as they could possibly be.

The sky began to pale. A man hurried past, buttoning his white chef’s jacket.

Nim signed to Selkie, and Selkie dived as silently as a whisper. Fred was already down at the bottom again; he was sure there must be seaweed somewhere. Nim kept on swimming and tried not to splash.

‘You’re up early!’ the chef called. ‘Trying to beat the rush?’

‘Yes,’ said Nim, and he hurried on by.

Nim knew it was too dangerous to stay any longer. They slipped out and back to the hold, with nothing but a quickly drying trail of water to tell where they’d been.