Ginger had always liked the old clock on the mantel in her grandmother’s house. It was made of dark wood, with a round glass face, golden hands, and a tiny brass pendulum that swung back and forth behind a little door. Every hour, it gave a deep, musical chime that could be heard throughout the house. But there was something peculiar about the clock. No matter how carefully her grandmother wound it, it never kept the correct time. Sometimes it ran too fast, sometimes too slowly, and occasionally it stopped altogether.

One evening, while visiting her grandmother, Ginger sat in the big armchair watching the pendulum swing. She was supposed to be getting ready for bed, but the fire was warm, the chair was comfortable, and the clock was making a particularly sleepy ticking sound. Before long, her eyes grew heavy, and she drifted off to sleep.

Then something very strange happened.

The clock struck thirteen.

Ginger opened her eyes. She counted the chimes again in her head. Thirteen? Clocks weren't supposed to strike thirteen. She climbed down from the chair and approached the mantel. The golden hands were moving, but not in the direction they were supposed to go. They were turning backward.

Tick, tock. Tock, tick.

Ginger leaned closer. The pendulum had begun swinging in circles, and the numbers on the clock face were slowly rearranging themselves. Twelve became eleven, eleven became ten, and ten became nine. Then the glass face shimmered like water, and a tiny golden door appeared where the number six should have been.

A voice came from inside. "Well, are you coming or not?"

Ginger looked around the room. "Who's there?"

"There's very little time, or rather, there's far too much of it. Either way, do hurry!"

The golden door swung open, revealing a staircase no bigger than a matchstick. But as Ginger reached toward it, the clock began growing larger. The mantel disappeared beneath her feet, the room stretched away, and suddenly she was standing before a clock taller than her grandmother's house. Ginger grinned. This was going to be interesting.

She stepped through the door.

Inside was an enormous room filled with clocks. There were grandfather clocks, cuckoo clocks, alarm clocks, pocket watches, and hundreds of tiny clocks hanging from silver chains. Some had hands that spun wildly. Others had no hands at all. One clock was shaped like a fish, and another had twelve little doors instead of numbers.

At the center of the room stood a very small man wearing a purple waistcoat and spectacles much too large for his face. His white hair stuck out in every direction, and he carried a pocket watch nearly as big as his head.

"Finally!" he exclaimed. "I've been waiting for you tomorrow!"

Ginger blinked. "Tomorrow?"

"Yes, tomorrow. Or possibly yesterday. I've lost track." He snapped his watch shut. "I'm Professor Tock, Keeper of the Hours, and we have a terrible problem."

"What kind of problem?" Ginger asked.

"Time is going backward, of course!"

Ginger glanced around. "Is that bad?"

"Bad? My dear child, it's a catastrophe! If we don't stop it, tomorrow will become yesterday, yesterday will become the day before, and eventually everyone will be babies again!"

Ginger considered this. "Even grandmothers?"

"Especially grandmothers!"

She imagined her grandmother crawling around the kitchen in a diaper and burst out laughing. Professor Tock did not laugh. He hurried toward a great silver clock at the far end of the room. Its face was as large as a wagon wheel, and its hands were spinning backward so quickly that Ginger could barely see them.

"The Great Clock has lost its Tomorrow," he explained. "Without Tomorrow, time has nowhere to go except backward."

"How do you lose a tomorrow?" Ginger asked.

"Carelessly, apparently. It slipped out sometime between midnight and breakfast."

Ginger examined the clock. Beneath its face were three little windows. The first said YESTERDAY, the second said TODAY, and the third said TOMORROW. The first two glowed with soft golden light, but the third was completely dark.

"Where should we look?" she asked.

Professor Tock pointed toward a winding hallway. "The Hall of Forgotten Hours. But be careful. Things there don't always happen in the right order."

Ginger started down the hallway, which twisted and turned like a long ribbon. Along its walls were hundreds of doors, each with a different time painted above it. From behind one door came the sound of children laughing. Behind another, someone was singing. A third smelled wonderfully of fresh bread.

Then Ginger heard a familiar voice. "Ginger! Come wash your hands. Supper's ready!"

It was her mother's voice.

She opened the door and found herself standing in the kitchen of her own house. Her mother was setting plates on the table, and her older brother was reaching for a biscuit. But something wasn't right. Her brother took a bite of the biscuit, and then the biscuit became whole again. He put it back on the plate, sat down, and stood up, all in the wrong order.

"That's peculiar," Ginger said.

Her mother turned toward her, but instead of speaking, the words seemed to fly backward into her mouth. Ginger quickly shut the door.

Farther along, she opened another door and found herself in her grandmother's garden. Flowers were closing their petals, butterflies were flying backward, and fallen leaves were leaping from the ground to fasten themselves onto branches. A fat orange cat was walking backward along the fence. It stopped, looked at Ginger, and said, "Meow," before the sound disappeared back into its mouth.

Ginger giggled. "You look ridiculous."

The cat gave her an offended look and continued backward.

At the very end of the hallway stood a small blue door with no number. Beneath it, a thin line of silver light spilled across the floor. Ginger knelt and peered through the keyhole. Inside, something was moving.

She opened the door.

The room beyond was filled with stars, although there was no sky. They floated everywhere, some large as apples, others smaller than grains of sand. In the middle of the room sat a little glass jar, and inside the jar was a bright silver spark that kept bouncing against the lid.

Ginger picked it up.

A tiny voice squeaked, "Put me down!"

She nearly dropped the jar. "Who are you?"

"I'm Tomorrow, obviously! And I've been stuck in here for ages!"

"How did you get inside?"

"I was curious," the spark admitted. "I wanted to see what Yesterday looked like, so I wandered off. Then the door closed, and I couldn't get out."

Ginger studied the jar. Its lid was fastened with a tiny silver lock.

"Where's the key?"

"That's the trouble. There isn't one."

Ginger tried twisting the lid, but it wouldn't move. She shook the jar gently, tapped the lock, and even tried prying it open with a hairpin she found in her pocket. Nothing worked. Then she noticed something written on the bottom of the jar.

What has not happened cannot be remembered.

Ginger read the words twice. "That's a funny thing to write on a jar."

Tomorrow bounced impatiently. "Well, can you open it?"

Ginger thought about the strange things she had seen. Her brother's biscuit becoming whole again. Leaves returning to branches. Words disappearing into mouths. Everything in the hallway was something that had already happened, happening backward. But Tomorrow hadn't happened yet.

"I think I know!" Ginger exclaimed.

She closed her eyes and imagined something that had never happened before. She imagined riding a purple elephant across the desert while a thousand tiny frogs played trumpets. She imagined a river made of lemonade and a moon that wore bright red boots.

The silver lock clicked.

Ginger opened her eyes just as the lid sprang free. Tomorrow shot out of the jar like a firework, scattering silver sparks across the room.

"I'm free!" it shouted. "I'm free!"

It zoomed around Ginger's head three times, then raced through the doorway. Ginger ran after it, her shoes tapping against the floor as the hallway began to shake. All around her, the doors flew open. Laughter spilled into the hall, clocks began chiming, and a shower of colorful seconds rained from the ceiling. One landed on Ginger's nose and made her sneeze.

By the time she reached the great clock, Professor Tock was hopping from one foot to the other.

"Did you find it? Did you find Tomorrow?"

Before Ginger could answer, the silver spark flew into the dark window beneath the clock face. The window blazed with light. For one long moment, every clock in the enormous room stopped.

Then the Great Clock gave a mighty shudder. Its hands slowed, stopped, and began moving forward.

Tick, tock. Tick, tock.

Professor Tock threw his hat into the air. "Wonderful! Magnificent! Tomorrow is back where it belongs!"

But just as Ginger started to celebrate, the great clock gave one enormous BONG. The floor tilted. The clocks began spinning, the walls folded inward, and Professor Tock's voice grew fainter and fainter.

"Remember, Ginger! Never put Tomorrow in a jar!"

Ginger tumbled backward through the golden doorway and landed with a soft thump in her grandmother's armchair.

She opened her eyes.

The fire had burned low, and the room was quiet. The old clock on the mantel was ticking steadily. Its hands showed exactly eight o'clock. Her grandmother appeared in the doorway.

"There you are, sleepyhead. I wondered where you'd gone."

Ginger sat up and rubbed her eyes. "Grandma, has your clock ever run backward?"

Her grandmother smiled. "That old thing? I wouldn't be surprised if it did."

Ginger looked toward the mantel. For the first time she could remember, the clock was keeping perfect time. Then something glittered on the arm of her chair.

It was a tiny silver key.

Ginger picked it up and held it against the firelight. On one side, in letters so small she had to squint, was a single word.

TOMORROW.

She slipped the key into her pocket.

That night, tucked beneath the covers, Ginger listened to the old clock chiming downstairs. She counted nine chimes, then ten, and finally eleven before she fell asleep.

And sometime after midnight, when everyone in the house was dreaming, the clock struck thirteen.

Just once.

Then it giggled.