That morning the sky was gray like a woolly blanket. It wasn't raining yet, but the air smelled of rain, and the clouds raced quickly over the rooftops of the town.

Lily, Ziggy, Skye, and Dash were inside Grandma's bakery. It was the warmest, most wonderful-smelling place in the world: bread and cakes baked there all day long, and the lovely smell wrapped around you the moment you opened the door.

The children were helping to knead the dough. Their little hands were white with flour, and Dash, quick as always, had gotten some on the tip of his nose too.

"Look at me, I'm a ghost!" he said, and everyone burst out laughing.

But Grandma wasn't laughing. She stood still in front of her old recipe book, her forehead wrinkled with worry.

"What's wrong, Grandma?" asked Lily, who always noticed everything.

"Oh, my darlings," Grandma sighed. "Today I wanted to make my special cake, the one I make only once a year. But the recipe page has gone missing. And I can't remember the very last ingredient."

The four children came closer, curious.

"I only remember one thing," Grandma went on, her eyes far away. "The last ingredient came from the water that sings."

"The water that sings?" repeated Skye, in her sweet little voice. "And where is it?"

Grandma spread her arms. "I don't know anymore, my little one. Too much time has passed."

Outside, the clouds grew even darker.

That was when they heard it.

CHUFF CHUFF.

A merry whistle, a magical sound, and in front of the bakery appeared a colorful little train, with shiny wheels and a chimney puffing little heart-shaped clouds. It was Toby the Magic Train.

Toby greeted the children and, as always, spoke in rhyme:

"Climb aboard, dear children, come along with me,
I'll take you where the water sings so happy and so free!
Down there sleeps a little spring with a soft and gentle voice,
Set it free to sing once more, and your heart will rejoice!"

The children clapped their hands. Grandma smiled for the first time that morning.

"Go, my treasures. And be careful."

They all climbed aboard the train. CHUFF CHUFF, and off they went, through fields and over hills, all the way to a place none of them had ever seen.

The train stopped in front of a lake. But it was no ordinary lake.

"How beautiful!" whispered Lily.

The water was so clear you could see all the way to the bottom, like looking into a glass. It was shallow and see-through, and the sun, peeking through the clouds, drew tiny golden dots upon it.

"This is Mirror Lake," said a little voice.

The children turned around. Beside them was a little dog with biscuit-colored fur. And, strangely enough, he smelled just like fresh-baked bread!

"Hello! I'm the little search dog. With my magic nose I can find anything that's lost." He sniffed the air, and his tail began to spin fast, like the blade of a fan. "And you're here for the water that sings, aren't you?"

"Yes!" said Lily. "We have to find the last ingredient for Grandma's cake."

The little dog looked at her and said, "Then you're lucky to be so tenacious."

The children looked at each other, confused.

"Tenacious? What does that mean?" asked Ziggy, scratching his head.

The little dog smiled. "Tenacious means that when something is hard, you don't give up. You keep trying, and trying again, until you make it."

"Then Lily is really tenacious!" laughed Dash. "She never gives up!"

But there was a problem. Mirror Lake was silent. There was no song, no music to be heard. Only silence.

The little dog sniffed again, and his tail spun hard. Then he grew sad.

"Do you hear it? Or rather... do you not hear it? The water doesn't sing anymore. And the star-flowers don't grow."

"The star-flowers?" asked Skye.

"They're tiny flowers that live in this lake. They smell like honey, and they're exactly the ingredient you're looking for. But they don't bloom anymore." The little dog lowered his ears. "Come and see."

They all came close to the edge of the water and looked at the bottom. And they understood.

On the lakebed were many things that didn't belong there: an old boot full of mud, some rusty cans, a few bags, and, right on top of a crack in the rock, a big stuck wheel.

"That crack is the Singing Spring," explained the little dog. "That's where the water gets its voice. But now it's all plugged up. As long as the lakebed stays dirty, the water won't sing and the flowers won't come back."

Lily clenched her fists. "Then let's clean the lake. Let's put it back in order!"

"It'll be like a treasure hunt," said Ziggy, his eyes shining, "but the other way around! Instead of taking things, we take them away!"

And so they began.

The water was shallow and warm. The children stepped in with bare feet and started gathering things up. Lily, tenacious, led them all. "You there, Dash! Skye, grab that can! Ziggy, help me with the boot!"

The boot was full of mud and made a funny noise when it came out of the water: SPLOSH! Everyone laughed. Little by little, the lakebed emptied out. The cans went into a sack, and the bags too. Only the wheel was left.

But the wheel would not budge.

Lily grabbed it and pulled. Nothing. Ziggy pulled with her. Nothing. Dash pushed, Skye pushed, the little dog pulled with his teeth. The wheel didn't move even a tiny bit.

"It's too heavy!" panted Dash.

"Let's not give up!" said Lily. "All together! One, two, three... GO!"

They pulled all at once, with all the strength they had. And at last the wheel moved, slid to the side, and came free! They all fell backward with a great splash into the water, laughing and soaking wet.

But right at that moment something happened.

DRIP. DRIP. DRIP.

It began to rain. And it was no ordinary rain. The drops, falling on the water, on the leaves, and on the stones, made a sweet music, like many little bells. It was the rain that sings.

"How lovely!" said Skye, her nose turned up to the sky.

But the little dog was not at ease. His tail was spinning fast. "Careful! When the rain sings, the lake fills up. The water is rising! We have to free the spring before it gets too deep!"

And indeed the water, which before reached their ankles, was now rising to their knees.

They looked at the crack. The wheel was gone, but inside the Singing Spring a tangle of bags and mud was still stuck, right at the bottom, in the deepest part of the lake.

"We can't reach down there!" said Dash, worried. "It's too deep!"

The water kept rising. The drops sang louder and louder.

Everyone hesitated. Everyone, except one.

Lily took a deep breath. "I'll go."

"Lily, it's dangerous!" said Skye.

"I'm tenacious, remember?" Lily smiled. "I don't give up."

The little dog stood beside her. "You won't be alone. I'm coming with you. I'm not afraid!"

And together they dove in.

Underwater everything was blue and silent. Lily kept her eyes open and followed the little dog, who swam ahead of her. And, funniest of all, every time the little dog sniffed underwater, instead of sneezing he blew lots of little bubbles out of his nose! PLOP PLOP PLOP!

They reached the bottom. The tangle of bags was there, stuck in the crack. Lily reached out her hands and pulled. It was hard. Her lungs were starting to ask for air. But she gritted her teeth and pulled again, tenacious as always.

And all at once, FLOP!, the tangle came free.

Out of the crack came a big bubble of air, then another, then many. And with the bubbles came a sound.

The water was singing.

Lily and the little dog came back up and poked their heads out just as the rain stopped and the sun began to shine again.

That was when the magic happened.

From the bottom of Mirror Lake, where before there had been only mud, sprang up many tiny star-shaped flowers. They opened one after another, and a sweet honey smell filled the air. And the water, free at last, sang a light melody, like a lullaby.

"We did it!" cried Lily.

The little dog sniffed a star-flower and his tail spun happily. "This is it! This is the ingredient you were looking for. Do you smell it? It smells like honey."

Gently, they gathered a few star-flowers. Not all of them: only the ones they needed, because the lake had to stay full of wonder.

CHUFF CHUFF. Toby was waiting for them.

They returned to the bakery wet, happy, and smelling of honey. Grandma saw them arrive and opened her eyes wide.

"The star-flowers!" she exclaimed, taking them in her hands. "Of course! This was the last ingredient! How could I have forgotten it?"

She put the flowers into the dough, and the bakery filled with a wonderful smell. Soon after, the special cake was ready: golden, soft, and as good as a hug.

While they all ate it together, Toby the Magic Train, from the window, spoke his last rhymes:

"The water that sings is a treasure so dear,
Whoever protects it stays happy all year.
Nature's a gift, treat it gently with care,
Whoever is kind hears it sing everywhere!"

And Lily understood something important. The lake had given back its song and its flowers only when they had treated it with care. Nature is like a gentle friend: if you respect it and keep it clean, it gives you its most beautiful things. But if you fill it with things that shouldn't be there, it stops singing. That's why nature is a precious gift, to be protected like the most beautiful treasure we have.

And that night, with their tummies full of cake and their hearts full of joy, the four children fell asleep dreaming of water that sang just for them.