The attic was a labyrinth of dusty memories and forgotten treasures. Ten-year-old Leo loved spending his Saturday afternoons exploring the stacks of old newspapers and trunks filled with vintage clothes. But today, he found something different hidden inside a small velvet-lined box: an ancient brass key, its handle shaped like a soaring dragon.

"Grandma, look what I found! Where does this key go?" Leo asked, running down the stairs two at a time.

Grandmother Elena looked up from her knitting, her eyes twinkling behind her spectacles. She took the key and ran her thumb over the intricate dragon handle. A faint smile touched her lips, but there was a hint of mystery in her expression that Leo hadn't seen before.

"Ah, the Dragon Key. I haven't seen this in forty years, Leo. It belonged to your great-grandfather, a man who believed that every lock had a story," she whispered.

"But I've tried every door in the house, Grandma. It doesn't fit any of them. Is it broken?" Leo asked, looking disappointed.

"Not broken, little one. Some keys aren't meant for wooden doors. Have you checked the old oak tree at the edge of the garden? The one with the hollow trunk?" she suggested.

Leo raced to the garden. The sun was beginning to set, casting long, golden shadows across the lawn. The old oak tree stood tall and gnarled, its branches reaching toward the sky like giant fingers. He found the hollow trunk, but instead of a lock, he saw only bark and moss.

"There's nothing here but wood and bugs! Grandma must be joking," Leo muttered to himself, turning to leave.

But then, a glimmer of light caught his eye. Deep inside the hollow, hidden behind a thick curtain of ivy, was a small iron plate with a keyhole. His heart hammered against his ribs as he inserted the Dragon Key. It turned with a satisfying 'click', and a small section of the trunk slid open.

"I don't believe it... a secret compartment!" Leo gasped, reaching inside.

Inside the tree was a leather-bound journal and a small wooden flute. He opened the journal to the first page: 'For the one who has the patience to look beyond the obvious.' As Leo played a single note on the flute, a group of fireflies began to dance in a perfect circle around him.

"It's magic! Why didn't you tell me, Grandma?" Leo yelled, running back to the porch with his discovery.

"Because some things are better discovered than told, Leo. Now, what does the journal say about the fireflies?" she asked, her smile wider now.

That night, as Leo read the stories of his great-grandfather's adventures, he realized that the key hadn't just opened a tree—it had opened a whole new world of wonder right in his own backyard.