NIM SANG AS she did her chores. She didn’t know how Alex would beat the Bad Guys, but she knew she would.

She did her charts and cleaned the hut; she dusted, shook and swept; got new palm fronds to make Alex’s bed; arranged sea-shells around the coconut pearl and her mother’s picture.

She weeded and watered the vegetable garden, ate two bananas and some peas for lunch; dug up three sweet potatoes and picked a lettuce, avocado, tomato and three handfuls of strawberries for later.

Then she flopped into the pool for a rest and a bath, and she and Fred watched the birds overhead.

They were flying inland, as if it was night.

Something was wrong.

Back at the beach, the sea lions were honking and restless, and Fred’s friends were zipping over the rocks, even the oldest scuttling like hatchlings.

Selkie was by the hut, barking anxiously for Nim.

Two more gulls flew past, and then a frigate bird.

‘Galileo!’ Nim called, running to the hut for a Troppo Tourist cap. ‘Have you got something for me?’

The big bird swooped, grabbed the stuffed fish and let Nim pull a note from his band.

Dear Nim

The birds say there’s a storm coming.

GO TO THE EMERGENCY CAVE.

Take the phone, laptop, solar panel, battery charger and other scientific equipment, and whatever else you have time for – but you are the only thing that matters. As soon as you see that storm coming, drop everything and get to safety.

If I can beat the storm I’ll be home tonight or early tomorrow.

Love (as much as a Jack loves a Nim),

Jack

Nim stared up at the sky. It was clear and blue, but the air was so still and heavy on her skin that she knew the birds were telling the truth, and she knew she had to do what Jack said. Nim didn’t like the Emergency Cave, but it was better than storms.

And it was much better than being on a boat in a storm, and much, much better than being on a boat in a storm when you don’t know the storm is coming.

‘I’ve got to warn Alex!’ said Nim, and dialled the number.

Alex answered on the second ring. ‘I’ve learned to sail and I’m on my way! I’ve just cast off from the Troppo Tourists’ ship.’

‘Get back on it,’ Nim begged.

But a roar of engines drowned Alex’s answer, and when the noise faded into the distance, Alex was saying, ‘I can see a dot where your island is. I should get there quickly – the captain told me there’d be some wind soon.’

‘It’s not a wind,’ Nim shouted. ‘It’s a storm!’

And then the satellite dish on the Troppo Tourist ship was too far away, and Alex’s phone went dead.

Nim dropped her phone into the wagon. She tucked the coconut pearl into her pocket and pulled down the satellite dish and solar panel. She loaded the picture of her mother, the torch, battery charger, laptop and satellite dish into her wagon, and tied the solar panel on top.

Fred climbed on top of that and nearly tipped it all over.

‘Walking’s good for you!’ Nim told him, lifting him down before he tipped it back the other way.

‘Meet us at the Emergency Cave!’ she called to Selkie. Chica would be safer on the sandy sea-bottom off Turtle Beach, but sea lions can’t stay underwater forever. Besides, if she couldn’t have Jack, Nim wanted Selkie in a storm.

At the Hissing Stones she had to leave the wagon and carry everything over the black boulders to the cave. The laptop was heavy and she was afraid of dropping it; the solar panel dragged and caught its corners in cracks in the rocks – but in four trips the whole load was safe in the cave.

‘Now stay there!’ she ordered Fred. Selkie had stopped to fish, but Nim blew the shell-whistle twice to tell her where they were.

The sea was still flat and calm; there wasn’t a breath of wind. ‘I bet I’m moving all this stuff for nothing!’ Nim said crossly as she tugged the wagon back to the hut for the books and Jack’s files of notes. They were heavy, and it took six trips to get them from the Stones to the cave.

‘One more load!’ she thought.

This time she grabbed her sleeping mat, water bottles, toothbrush, comb, clothes and barometer, throwing them into the wagon any old way because now she could see in the distance a whirl of dark air, black and yellow as a bruise, moving across the eastern sky.

It was coming fast; faster than Fred after coconut. Nim dropped the wagon handle and flew across the grassland. The wind hit just as she reached the Black Rocks.

It knocked her backwards and whipped her hair; it tore at her eyes and ripped the breath out of her lungs.

Selkie grunted encouragement, Fred skittered, and Nim scrambled the rest of the way on her hands and knees. As she reached the mouth of the cave, the first thunder boomed and the rain came down like a surf wave on the rocks.

ALEX PULLED HER sails tight, the way the instructor had shown her. The Troppo Tourists ship disappeared; she was alone on a wide, empty ocean in a boat as small and frail as a bathtub toy …

I wish Nim was right and I was my Hero! she thought. But at least I can take notes about sailing – the gentle breeze, the interesting clouds …

The interesting clouds came closer, fast. They were dark grey and swirling. The gentle breeze jumped to a full-force gale, and Alex felt like the Hero in a legend who let the winds escape from the bag they were trapped in.

That was when she remembered that she’d left her life-jacket on the ship.

‘I’ll tie myself to the mast,’ she said, but before she could reach it, the rain started.

‘Like being in a carwash!’ Alex thought. ‘Without a car!’ The mast suddenly seemed a long way away, but just beside her was a metal ring with a rope through it. Alex yanked the rope free and tied one end to the ring and the other around her waist.

Then there was nothing to do except try to steer, and wonder whether the rope she’d pulled off was important, and did it matter anyway when the boat was balancing on skyscraper-high waves?

Maybe they weren’t quite as tall as skyscrapers. Maybe they weren’t much higher than a cottage. Tall enough! thought Alex as she roller-coasted from one to the next.

A fork of lightning exploded into a wave; a crash of thunder hit her ears like a boxer’s punch.

Alex threw herself onto her stomach and clung to the tiller. Then the next wave was under her and the wind was howling and hurtling her towards the smudge of Nim’s island – ‘Faster than a city train!’ Alex guessed.

She couldn’t decide whether that was a good thing or not, but she was beginning to understand how her Hero felt when she sent him adventuring: terrified-thrilled; sure he was going to die and so alive that he never wanted to stop.

CRACK!

Her sails billowed like a balloon; the mast lifted and toppled off the boat. There was a sad flap of white and her mast and sails sank out of sight.

‘So now it’s a rowboat,’ Alex decided.

She pretended that she was her Hero, because he wouldn’t mind that his computer and suitcase had washed overboard and were at the bottom of the ocean.

He wouldn’t even be scared when he saw that the mast had taken a chunk out of the bottom of the boat as a going-away present, and the sea was coming in to take its place. A Hero would simply take off his hat and bail, so that’s what Alex did.

The problem was that even when she was being a Hero, the waves were still monstrous, the rain was still pouring and the wind was still roaring, and each time they slammed across a wave, more of the wave came into the boat, and no matter how fast she bailed, less of it went out. The hole was getting bigger, and the bigger it got, the faster the water poured in, and the faster the water poured in, the bigger the hole got.

And the bigger the hole got, the faster the boat sank, as if it was tired of being a boat and wanted to try being a submarine.

And Alex was still tied firmly to it.

‘If only I’d gone to Brownies,’ she muttered, frantically trying to untie the pulled-tight rope, ‘and learned to tie reef knots, or whatever kind of knot it is that you can untie when you need to!’

She tried to undo the knot around her waist first, but when she’d pulled it so tight that she could hardly breathe, she gave up and worked on the other end. She tried with fingers and tried with teeth, spluttering and choking, because now the knot was quite a long way under water.

Which is where I’m going to be, too, Alex thought, and even though she didn’t much like being in the top bit of the ocean, she thought she’d like the bottom even less.