EDMUND HAD BEEN telling the truth when he said that he liked being alone.

But he loved camping alone even more than he’d imagined. He loved having his own tiny tent, with nothing in it except his pack, sleeping bag, and four interesting shells he’d picked up on the beach yesterday. He kept the tent flap open all night so he could see the stars, and hear the sea whispering through his dreams.

It would have been perfect if Tiffany and Tristan hadn’t been around. He’d only been on the island for two days the first time he came, and for most of it Nim hadn’t liked him at all. He didn’t quite know how to be friends with her in front of other kids.

The other not-quite-perfect part was thinking about Dr Ashburn and Professor Hunterstone. He’d only met them once, but he liked them. Now he kept thinking of Selina’s voice on the phone yesterday. ‘It’s okay,’ she’d said, even though she’d already had to stop talking once to run and be sick. ‘Lance and Leonora can do the science just as well as Peter and I can. And they’ll take you with them to meet the Lowes and their boat – they’re very kind.’

The problem was that Edmund couldn’t like Leonora and Lance. He didn’t exactly not like them, but his skin prickled whenever they were around. It was uncomfortable having prickly skin.

HE SLIPPED BETWEEN the tents and down to the beach. The sun was rising pink and gold behind Fire Mountain, but in front of him the sky was a pale grey-blue, and so was the sea. The tide was washing the beach fresh and clean. Edmund felt the sand tickle between his toes. Only a bird had been there before him; when he turned around his footprints were beside the pattern of its webbed feet, as if he’d been walking with his pet seagull.

It would be good to have a bird as a friend, he thought, like Nim had Fred and Selkie. Edmund had a dog at home, a goofy, loving labrador named Sam, who was as much a part of the family as anyone else. But there was something wild and wonderful about Nim’s animal friends. They were free to do whatever they wanted, and what they wanted was to be with Nim.

At the end of the beach was a point of worn grey rocks covered with sea lions. Some of them were sliding into the water for their morning fish, some were dozing and some were watching him – but they were all big, and there were a lot of them.

‘I’m a friend of Nim’s,’ Edmund told them. ‘And Selkie’s.’

It was hard to tell if the sea lions had understood. Edmund decided to walk on the grass for a while.

On the other side of the point, the reef met the rocks in a huge ring. The sea shushed in and out through a hole in the reef, but inside the cove, the water was so calm and clear that he could see the sand and giant clams on the bottom, and the sea horses and tiny bright fish darting in between.

Edmund stood on the edge of the rocks watching them. He lay on his stomach and went on watching. Finally he jumped in. He swam with the polka-dot fish and dived down to see the clams up close. He floated on his back and let the sun warm him, and swam and dived again. He had never felt so free.

NIM MET JACK and Alex on the trail home.

‘I wanted to walk now if I’m going to hide in my studio all day,’ Alex explained.

Nim hated the thought of being stuck anywhere that long, even somewhere like Alex’s studio, with its big open windows looking out to the forest.

‘I guess I’d rather meet people than stay inside,’ she said.

‘Even Tiff-Tris?’ Jack teased.

Nim didn’t think there was anything funny about the twins.

‘I guess so,’ she said. ‘At least their little brother is cute. He’s a lot nicer than they are.’

‘Everyone has something good in them,’ said Alex. ‘Some people just hide it at first.’

‘Luckily you’ve got two days to find it,’ said Jack. ‘Because I want you to stay with the other kids and make sure they don’t fall into any trouble while they’re here.’

Nim knew there was no point in arguing – but at least they’d forgotten to ask where she’d been. She decided to wait and tell them about the fern fossil later. A surprise like that would be a present for Jack as much as for Leonora. Even more, because it would always be here on the island.

In fact, it was such a good present that Nim decided she didn’t feel guilty about going somewhere dangerous without telling anyone.

THE OTHER TWO tents were still closed and quiet when Edmund got back to the camp. He took his water bottle and toothbrush up to the freshwater pool. He filled the bottle at the waterfall and brushed his teeth out on the hill. Looking down over the grasslands to the sea was much better than looking at the bathroom sink at home.

But he’d already used half his water. He went back to the waterfall. Nim was there filling a bottle too.

‘Did you fall in?’ she asked.

Edmund had forgotten he was still wet. ‘I went swimming in Keyhole Cove – it was amazing! I saw sea horses, and clown fish, and …’ His voice trickled away when he saw Nim’s expression. ‘Was that okay?’

Nim didn’t know how to say that she’d been imagining how much he’d like it when she showed it to him, and now he’d spoiled it by finding it himself. ‘Just don’t take Tiffany and Tristan,’ she said.

‘They’re too cool to go anywhere with me anyway.’

‘But Jack said all the scientists are going to do science stuff all day,’ Nim began.

‘And the kids are supposed to hang together?’ asked Edmund.

Nim pictured them all hanging upside down like the bats in the cave. She laughed, but it didn’t change the problem. It was her job to keep the other kids safe on her island, but if Tiffany and Tristan mocked one more thing she truly might explode – she didn’t want to share her discovery with them until she knew exactly what it was and how good it was.

But if she didn’t share it now, she wouldn’t have time to figure out exactly what she’d found before everyone left. She wanted to show her fossil to Leonora more than she didn’t want to spend the day with the twins.

And maybe, just maybe, they’d be different after spending a night on the island. Maybe they’d wake up realising what a special place it was, and how amazing Selkie and Fred were. Maybe they’d even want to be friends.

‘It’ll be okay,’ Nim told him. ‘I’ve got something really cool to show you. Even Tiff-Tris will think so.’

BACK AT THE camp, everyone was busy getting up and deciding what they should do for the day.

Anika wanted to take their boat out to study the algae on the faraway reef and compare it to those living on the coral around the island. Ryan wanted to test water samples and temperatures all the way in between.

‘I’ll take you,’ said Jack. ‘The sailboat won’t disturb the water the way a motorboat does.’

‘No more boat!’ said Ollie.

‘You can stay with Tiff-Tris,’ said their mother.

‘But …’ the twins whined.

‘We’ll be working,’ Anika told them. ‘Ollie will be much safer here with you than on the boat. Take him to the beach, or whatever you want – just keep an eye on him.’

‘I’ve got two eyes!’ said Ollie, holding up two fingers.

‘So do I,’ Nim said. She smiled and held up two fingers too.

‘And I’m this much old,’ said Ollie, putting up three fingers.

Human babies take a lot longer to grow up than sea lions and iguanas! Nim thought.

Jack grinned at her as if he knew what she was thinking.

‘Where do you want to explore?’ he asked Lance and Leonora.

‘The cliffs and the mountain,’ said Lance. ‘Whether it’s algae in rock pools or some other undiscovered vegetation, the perfect source of biofuel must be out there somewhere.’

‘Unless you have any ideas for us, Nim?’ asked Leonora.

Nim shook her head. It would completely spoil the surprise if they came with her.

But she wasn’t used to keeping secrets, and she knew her face was glowing as hot and red as a frigate bird’s throat. She hid it against Selkie’s warm neck.

Hmphh! Selkie snorted. She knew that Nim wasn’t really cuddling her.

WHEN ANIKA AND Ryan had sailed off with Jack, and Lance and Leonora were in their tent getting ready for the day, Nim announced to the others that she had something amazing to show them.

‘What kind of amazing?’ asked Tiffany.

Tiffany’s voice was quite loud. Nim beckoned for them all to come further away from the tents.

‘A cave,’ she whispered.

‘Cool!’ Tristan started to say, but stopped when his sister glared at him.

‘We’ll have to be quiet because of the bats,’ Nim added. ‘Bats!’ Tiffany shrieked.

‘Just the mothers and babies,’ Nim explained. ‘They’re sleeping now it’s day, so we can’t disturb them.’

‘So why would we want to go there?’ Tiffany demanded.

‘I think I’ve found a fossil,’ said Nim.

‘And you want us to help dig it out?’ Tristan asked.

‘We can’t dig out the walls in a bat nursery!’ Nim shouted, horrified. She remembered that she was trying to be quiet and started again. ‘I want to clean it up so we can see it.’

‘If you show it to Leonora, she’ll want to take it out,’ Tiffany said.

‘No, she won’t,’ Nim snapped. She didn’t understand why Tiffany had to be so nasty about Leonora. ‘Jack said everyone had agreed: the research is just observation. No one can do anything that changes the island.’

Edmund nodded. ‘That’s what Dr Ashburn said.’

‘And we got about sixteen hundred lectures about it before we came,’ said Tristan. ‘So let’s go see the cave.’

Nim breathed a sigh of relief. She hadn’t meant to snap, because she really needed them to go with her. Stay with them and make sure they’re safe, Jack had said.

‘But we’re supposed to be looking after Ollie,’ said Tiffany. ‘I’m not taking him all the way back up the mountain.’

Ollie had dug a big hole in the sand. Now he was sitting in it and using a plastic mug to pour the sand back in from the edges. Nim trickled a handful over his toes as she tried to stop the volcano inside her from exploding.

They’re only here for two more days. That was the other thing Jack had said. Even Fire Mountain can last that long without erupting.

Fire Mountain hasn’t met Tiffany, Nim thought rebelliously.

SO FIFTEEN MINUTES later, when Tiffany was still telling Tristan they couldn’t go and Tristan was saying he could piggyback Ollie, and Tiffany was saying all over again that she wasn’t going into a cave with bats for anything, and it probably wasn’t a real fossil anyway, a bit of steam hissed out of Nim’s eyes, and she said she didn’t care what anyone else did, she was going.

‘So am I,’ said Edmund, coming out of his tent with his daypack.

‘We’re not,’ said Tiffany.

Tristan looked miserable and didn’t say anything.

Ollie was too busy burying his legs in the sand to listen.

NIM WAITED A few more minutes, until Leonora and Lance had come out of their tent and waved goodbye. They were heading towards Frigate Bird Cliffs. Perfect! Nim thought. She and Edmund were going exactly the opposite direction. And she’d asked the others to come – it wasn’t her fault they were staying behind.

She was nearly singing as she picked up her backpack. It had her bamboo drinker full of fresh water, two bananas, a big chunk of coconut and a chisel from her toolbox.

‘Would Fred ride on my shoulder?’ Edmund asked.

‘He might if you give him this,’ Nim said, breaking off a piece of coconut.

Edmund sat down beside the iguana and held out the coconut. Fred grabbed it and gulped it down. He looked across at Nim.

‘It’s okay,’ she said. ‘You can go with Edmund for a while.’

Fred scampered up to Edmund’s shoulder. Edmund stood up carefully, and felt the small sharp nails clinging. ‘You’re tickling!’

Nim laughed. She was so used to Fred that she hardly felt the tickle anymore, but she’d never thought how it would feel to someone else. It was almost as if she’d never seen him properly before. A bubble of love swelled inside her for her small spiky friend.

Her big smooth friend wasn’t nearly so happy. Selkie humphed and snorted when Nim told her they were going back to the caves. ‘You could stay with Tiff-Tris and Ollie,’ Nim said.

The sea lion snorted even harder and galumphed down to the sea without looking back.