She found the key on the internet.

It seemed silly, a little, to buy a physical and tangible thing like that to open up a locked trunk in a dream. But it was necessary, she was sure. She'd been trying to get into the trunk in the bedroom of the house of doors - the house she returned to over and over again in her lucid dreams - for years. For as long as she could remember.

The trunk, solid and wooden, banded with brass and locked. It was impenetrable. She'd tried peering through the keyhole, picking the lock, everything. She'd conjured keys before, even, but they didn't fit or wouldn't turn in the lock - most never even got into the keyhole. It was ridiculous. She could control almost everything in the environment in the house of doors, but not the trunk.

It had gathered dust for fifteen years. She'd gotten tired of trying to break into it. Gotten tired of trying to puzzle it out or bash it open. It was an enigma, and she just accepted it. And then she saw the key.

It was wrapped with copper wire, with blue enamel dragonfly wings attached to it. Tiny clockwork cogs accented the bale. It was the right key. She knew.

And so she bought it, and then brought it with her, holding it tightly as she fell asleep, like a magic talisman. Nervous, excited, and daring to dream into her house of dreams for the first time in ages.

She crouched on the bedroom floor, holding the key. It was a little different here, the transition from reality to dreams modifying it a little. It sparkled, for one. And the metallic wings fluttered against her palm gently. She stared at the trunk, suddenly nervous. What could be in there, locked away so tightly all this time?

She dared. She pushed the key gently against the lock. It clicked, it turned, the wings beat slowly. The trunk lid opened, ponderous, on its own. It creaked. Inside was another world, and she fell through, laughing. It was a key to her imagination after all.