It was a warm, golden summer evening, the kind that seems like it will never end. On Half-Moon Beach, the sky was turning pink and purple, and the swallows were flying low over the water, brushing the waves with the tips of their wings.

Ziggy, Lily, Skye, and Dash were having dinner sitting on a big checkered blanket, together with their parents. There were tomato sandwiches, slices of fresh watermelon, and a bottle of apple juice that sparkled in the sun.

"Look at the colors!" said Ziggy, pointing at the sky with a finger sticky from watermelon.

"It looks like Grandma's cake," laughed Dash, "the one with jam on top."

Lily shook her head with a serious look. "To me it looks like a princess's cape," she said, tucking her curls behind her ears.

Skye said nothing. She sat quietly, watching the sea, with her knees pulled up to her chest. She liked listening to the sound of the waves, which was like one big slow breath.

All of a sudden, from far away, came a rumble. It was low and deep, like a big tummy growling because it's hungry.

"Hey," said Andrew, Skye's daddy, looking up. "There's a thunderstorm, but it's very far away. Nothing to be scared of."

"It rumbles like our tummies when we're hungry!" said Dash, and everyone giggled a little.

Meanwhile, behind the hills, the moon was beginning to rise. It was huge, round, and so full of light that it looked like a big silver cheese. Its light spread across the sea like a shining road.

But there was something strange. On the tip of the rock, at the end of the beach, stood the Old Star Lighthouse. Every night, forever, it lit up its big yellow light to help the fishermen's boats find their way home. That evening, though, the lighthouse was off. Dark. Quiet as a candle blown out.

"Mommy," said Skye in a tiny voice, "the lighthouse isn't turning on."

Elise, her mommy, turned to look. "You're right, sweetheart," she whispered. "It really is off."

Farther out, on the silvery sea, you could see a little boat. It had a light that swayed back and forth. But the little boat wasn't going anywhere: it was spinning in circles, like a little spoon in a cup. It couldn't find the way to the harbor.

"The fishermen are lost," said Lily, squeezing her sandwich tightly.

The storm rumbled again, a little bit closer.

Right at that moment, from the sand dunes, came a sound the children knew very well.

"CHUGGA CHUGGA! CHUGGA CHUGGA!"

It was Toby the Magic Train! He came swaying along the sand, with his smoke shaped like little hearts. He stopped right in front of the children, greeting them with his little horn.

"Good evening, dear children with hearts pure as gold,
the sea hides a treasure that's waiting, behold!
The moon is so high, but the lighthouse won't glow,
deep down in the water, there's a friend you should know.
Climb up on my back, there's no time to delay,
a wonderful something is waiting today!"

The children looked at each other with eyes wide open in wonder. They kissed their parents quickly and hopped on the train, which set off right away toward the shore.

But something magical happened. Toby didn't stop at the water's edge. He kept on traveling right on top of the water, as light as a feather. He stopped where the sea grew a little bit darker.

"Before you go down, you'll need these," said Toby, and with a little tap he made four pink seashells appear. "They're magic shells. Hold them to your ear and you'll be able to breathe underwater."

Skye took her shell with open hands. It was warm and smelled like salt. She held it close to her ear. Right away she heard a tiny whisper, as if the sea were saying to her: "Come, come."

"Let's go!" said Skye, who usually didn't talk much, but now had something important to do.

The four friends jumped in together. SPLOSH!

And the magic happened. Underwater they could breathe, talk, and see perfectly. Every time the moon sent a ray down to the bottom of the sea, the water lit up as if it were full of tiny stars.

"Wow…" whispered Dash.

They drifted down gently, among colorful fish and plants that swayed in the current. They arrived at a beautiful place called the Whispering Coral Bowl. A bowl is like a round dish dug into the sand, and that one was full of pink, yellow, and purple corals. The corals were whispering, which means they were talking very softly, like when Mommy tells a bedtime story.

In the middle of the bowl, sitting on a rock, there was a little crab. He had a shiny red shell and two big claws that were shaking a little. All around him was a pile of beautiful things: shimmering shells (which means with lots of colors that change in the light), a starfish that glowed like a little lamp, long seaweeds soft as spaghetti, and a big empty turtle shell, left there a long time ago.

"Hello," said Skye, coming closer.

The little crab gave a frightened jump. "Ohhh!" he squeaked. "My name is Coralin. Are you… are you here for the little boat?"

"What little boat?" asked Ziggy, curious.

Coralin let out a sigh. "The big fish told me the lighthouse is off. The fishermen's boats are getting lost. So I gathered everything I need to build a light-boat: you put it on the sea and it lights up the way for the fishermen. I have the shell here to make the hull, the seashells for the edges, the seaweeds to tie things together, and the starfish that shines like a little sun. Everything is ready."

"So? What are you waiting for?" asked Lily.

Coralin lowered his eyes. His claws began to shake. "I… I can't get started. I try, but when I have to put down the very first piece, I freeze. I count: one… two… and then my claws shake and I can't do it anymore. I'm scared of getting the very first piece wrong. Because if you get the first one wrong, you get everything wrong."

At that moment, from above, came another rumble of the storm. Closer than before. The moon's light at the bottom of the sea grew a little darker, because a cloud was passing over it.

"Coralin, we need to hurry," said Dash, worried. "The storm is coming!"

But Coralin was shaking more and more. Everyone was looking at him. Ziggy was clenching his fists. Lily had a wrinkled brow. Dash was hopping from one foot to the other.

Then Skye did something that came naturally to her. She walked up to Coralin calmly, sat next to him on the rock, and took one of his claws between her hands. The claw was cold and shook like a little leaf.

"Coralin," she said in a soft voice. "You don't have to do this alone. We'll do the first piece together. You tell me what goes first."

Coralin lifted his eyes. They were like two tiny shiny black drops.

"The… the turtle shell," he said in a thin little voice. "It goes here, on the bottom, because it's the hull."

"Good," said Skye. "Now we'll pick it up together."

Skye wrapped her hand around Coralin's claw. Together, calmly, they lifted up the shell and placed it in the middle of the bowl. When the shell touched the bottom, it made a sweet sound, like a little bell underwater.

Coralin's eyes opened wide. "I did it," he whispered. "I really did it."

"Yes," smiled Skye. "And see? It wasn't so hard."

Then something wonderful happened. Coralin's claws stopped shaking. He picked up a shimmering shell with confidence and placed it on the edge of the hull. Then another. Then another one.

"Quick, friends!" cried Coralin. "We have to hurry!"

Ziggy zipped off like an arrow to gather more shells scattered around the bowl. Lily, as tough as ever, braided the long seaweeds to make ropes. Dash, fast and funny, ran back and forth bringing the right pieces at just the right time. Coralin tied, arranged, and built.

At the top of the little boat, in place of a sail, they placed the starfish that glowed. It shone with a warm yellow light, just like the light of a real lighthouse.

Meanwhile, above them, the water was getting darker and darker. The storm had almost arrived.

"It's ready!" cried Coralin.

All together they pushed the light-boat upward. It passed through fish, through moonbeams, and reached the surface with a little PLOP.

The children swam up behind it. When they put their heads out of the water, they saw something magnificent. The light-boat floated on the sea like a tiny moon fallen from the sky. The starfish gave off a golden light that reflected on the silvery water and made a road.

And the road went all the way to the fishermen's boat.

The fishermen, who had been spinning in circles for so long, saw the light. They started rowing along that shining road. They went straight as an arrow, all the way back to the harbor.

Right at that moment, a big drop of water fell on Skye's nose. PLINK.

"The storm is coming!" said Lily.

But now it wasn't a problem anymore. The fishermen were safe.

On the shore, half hidden behind a rock, Coralin watched his little boat shining far away. His eyes were shiny, but not from fear. They were shiny with joy.

"One…" whispered Coralin, "two… three! I counted all the way to three!"

And he laughed, happier than he had ever been.

The children waved at him, and Coralin waved back with both his claws. Then, gentle as he had come, he drifted away among the whispering corals.

From the beach came that famous sound again: "CHUGGA CHUGGA!"

Toby was waiting for them. They hopped on the little train, wet but happy.

"Brave little children, our journey is done,
the moon saw it all, sweet dreams have begun!
To do something grand and important and true,
a small gentle gesture is all that we do.
Who holds out a hand when a friend feels afraid,
gives a gift to the heart that will never fade."

The little train set off toward the beach, leaving behind a trail of little smoke hearts.

When they got back to their parents, the first raindrops were falling gently on the sand. Skye ran into Daddy Andrew's arms and laid her head on his shoulder. She fell asleep almost right away, while far off you could still see a tiny golden light on the sea.

And in Skye's dream, a tiny crab voice whispered: "Thank you. Now I know how to begin."