It was a morning of warm sunshine, the kind where the grass still sparkles with dew. Ziggy, Lily, Skye and Dash were playing orchestra in the garden. They had grabbed pots, lids and wooden spoons, and they all banged together making a cheerful racket.

"I'm the drum!" shouted Dash, hopping from one foot to the other.

"And I'm the cymbal that goes CLANG!" laughed Ziggy, clapping two lids together.

Lily was conducting with a ladle as if it were a magic wand. Skye, though, tapped her hands gently on the bottom of a pot and listened. She loved hearing how every sound had a different heart.

Then, from the far end of the garden, came a sound they knew well.

"CHUFF CHUFF! CHUFF CHUFF!"

It was Toby the Magic Train, all shiny, stopping among the blades of grass and puffing colorful smoke. The children ran to him, happy. Toby opened his little doors and said, as always, in rhyme:

"CHUFF CHUFF, good morning, dear children so gentle and bright,
today we'll fly high, up past the yard, out of sight:
there's a tired little light that has lost its own song,
and whoever can hear it will help it grow strong."

The children looked at each other, curious. A light that had lost its song? What could that mean? They climbed aboard laughing, and Toby set off swiftly through the clouds.

When the windows opened again, the garden was gone. There was the sea. A big grey sea, and up high, on a rocky cliff, stood a lighthouse. A lighthouse is a very tall tower that at night lights up a very bright light, to tell the boats: "This way! Home is this way!" But this lighthouse had a weak, flickering light, that switched on and off like a tired candle.

It had also begun to rain. Not heavy rain: tiny light drops that went "tick tick tick" on the stones, like little fingers knocking ever so gently.

"Look at the boats!" said Lily, pointing at the harbor.

Down near the shore, many boats sat still. Their ropes had all knotted up during the last storm, tangled like spaghetti on a plate. Not one boat could set off.

"Poor things," whispered Skye. "They want to go and they can't."

The four friends climbed down among the rocks, careful not to slip. Ziggy and Dash raced to see who could find the biggest puddle. Lily looked for shells. Skye, though, had stopped. She had heard a tiny sound, a sniffle, like when someone is trying not to cry.

She went slowly behind a rock. And there, curled up, with her flippers pressed to her chest, was a seal. She had big shiny eyes, and she smelled of salt and sweet seaweed, like a sea candy.

"Hello," said Skye in a gentle voice. "I'm Skye. Don't be afraid."

The seal flinched and pulled back. "You... you saw me? I always hide."

"What's your name?" asked Skye, sitting down beside her, in no hurry.

"Melody," answered the seal. "But it's a wrong name now. Because I don't make music anymore."

Meanwhile the other three had arrived too. They sat down quietly, so as not to frighten her.

"Why don't you make music anymore?" asked Lily.

Melody sighed. "A long time ago I used to play. I would beat my flippers on the water, like drums, and my music rose all the way up to the lighthouse. The lighthouse heard my song and woke up, and lit its big light to guide the boats home. He and I were friends. One night, though, there was a storm, and I... I played one wrong note. Just one. But the boats got lost among the waves. Since that night I've never had the courage to play again. And the lighthouse, without my music, fell asleep."

"So that's why the light is so tired," said Ziggy softly.

"I still keep one thing," added Melody, and she lifted a flipper. Underneath was a spiral shell, glowing. "This shell keeps the echo of every song."

"What does keeps mean?" asked Dash, scratching his head.

Melody smiled just a little. "To keep means to hold something precious safe, with care. Like when your mom holds your hand while you cross the street."

"Ohhh," went the children together.

"If this shell could sing near the lighthouse again," Melody went on, "maybe its light would wake up. But it fell to the bottom of the sea, inside an underwater cave. It's far away. And I'm too afraid to go there."

Skye looked at the sea. The little drops kept going "tick tick tick".

"I'll go," she said.

Everyone looked at her. Andrew, Skye's dad, had just arrived among the rocks with his umbrella, and he made his usual joke: "Careful, sweetheart, if you drink the whole sea there'll be no water left for the fish!" But Skye knew: she had to learn to swim underwater. And she had never done it before.

She came to the shore. She took a big breath and dived in.

SPLASH!

She went under, but as soon as she tried to open her eyes she gulped a mouthful of salty water and came back up coughing. "Ptooey! Ptooey! Yuck!"

"Try again!" Lily cheered her on.

Skye tried again. This time she went down a little, but a foot slipped out of the water and she spun all the way sideways, like a pinwheel. She came up with seaweed on her head. Dash burst out laughing: "You look like a mermaid with a green wig!" And Skye laughed too, even though she was tired.

She tried a third time. And missed again. And a fourth. And missed once more.

She sat down on the rock, out of breath and with slightly sad eyes. Melody came closer and said softly: "See? It's too hard. It's better to stop. I stopped too."

And that was when the most important thing in the whole story happened.

Skye took one of Melody's cold flippers in her hands. She looked into her shiny eyes and said: "You know what, Melody? I make mistakes lots of times too. I drank the sea, I spun like a top, I filled my head with seaweed. But that doesn't mean I'm bad at swimming. It only means I'm learning. You learn by making mistakes. And if I try again, one little piece at a time, in the end I'll do it."

Melody stayed silent. Then two tears slid down her face, but this time it was a gentle cry, the kind that loosens a knot inside. She looked at the water. And, with the tip of a flipper, she touched it.

TAP.

Just one sound. Small.

Then two flippers. Tap-tap.

Then three, all together, like she used to when she was happy: "pata-pum-pum-pum!"

"You did it!" shouted Ziggy. "You played!"

Melody's eyes were shining. "I... I got a bit wrong. But it's wonderful all the same!"

"Then let's do this," said Skye, standing up again. "You play for me. And I, listening to your music, won't be afraid to go under anymore."

Melody nodded. She began to beat her flippers: pata-pum-pum-pum, pata-pum-pum-pum. And her music was like a gentle little hand on Skye's back.

Skye breathed. She dived in. And this time, with Melody's song in her ears, she went down, down, among the silvery fish and the swaying seaweed. She saw the cave. She saw the shell glimmering in the dark. She reached out her hands. And she took it.

She came up with a great SPLASH, holding the shell tight to her chest, laughing and crying with joy at once. "I did it! I tried again and I did it!"

Everyone on the shore clapped their hands. Andrew even had shiny eyes, and he pretended it was the rain.

But it wasn't over yet. Melody looked at the lighthouse, up there, with its flickering light. Then she looked at the shell. And she understood it was her turn.

"I have to play for the lighthouse," she said. "Like I used to. Without being afraid of making mistakes."

She took a big breath. And she began. She beat her flippers on the water, and the shell gathered the echo and sent it up, toward the cliff: pata-pum-pum-pum, tick tick tick went the rain, and the music rose and rose.

She played a wrong note. She stopped for an instant, her heart trembling. Then she looked at Skye, who was smiling at her. And she started again. Because making a mistake is not the end: it's just a little piece of the song.

And then, slowly, the lighthouse's light came on. First weak. Then stronger. Then very bright, warm and golden, sweeping across the whole sea like a hug of light.

And down at the harbor, as if by magic, with the light and the calm returned, the knots in the ropes began to loosen all by themselves, one after another. The boats moved on the water, free at last to set off.

"Hooray for Melody!" the children shouted. "Hooray for the lighthouse!"

Melody glided over the water, drawing great spirals of joy. "Thank you, Skye," she said. "You taught me that making mistakes doesn't make me a bad seal. It makes me a seal who is learning. Just like you."

Skye hugged her tight, all soaking wet, and the two of them held each other close under the gentle rain.

A little later, behind them, came the familiar "CHUFF CHUFF". Toby the Magic Train was waiting to take them home. They waved goodbye to Melody, until she was just a little dot playing happily among the waves.

When they were all aboard, Toby said, as always, in rhyme:

"CHUFF CHUFF, we head home now with hearts full of cheer,
the light has come back, and there's nothing to fear.
Whoever slips, then tries again, is never alone:
they find fresh courage, and away they have flown."

The children rested their heads against the window, tired and happy. Skye closed her eyes with a smile. And as Toby raced through the clouds, she still seemed to hear, far, far away, the pata-pum-pum-pum of a seal who had found her music again.