Chapter 4: The Drowning City

The water was up to Emma's knees now, and rising fast. The chamber's walls were covered in moving paintings - scenes of Venice sinking inch by inch over the centuries. The backward-moving clock in the center made a sound like a heartbeat underwater.

Emma held the bear-shaped key tightly. The keyhole was just above the water line, but it wouldn't stay that way for long. She waded through the cold water, the box held high above her head.

As she inserted the key, something strange happened. The water stopped rising. The clock's backward movement slowed, then stopped. A new set of symbols appeared on its face - coordinates pointing to Prague.

But before Emma could breathe a sigh of relief, the chamber began to shake. The paintings on the walls came to life. She saw Venice in different time periods - some she recognized from history books, others completely alien.

In one painting, Venice was completely underwater, its buildings covered in coral and seaweed. In another, the city floated in the sky, held aloft by giant balloons.

A voice echoed through the chamber - her grandfather's voice, but younger than she remembered.

"Emma," it said, "you're seeing what could have been, and what might still be. Time is a river with many branches. Choose wisely."

The shaking grew stronger. Pieces of the ceiling began to fall. Emma grabbed the box and ran back to the boat. As she rowed through the tunnel, the water behind her turned to ice, trapping the chamber forever.

Back in St. Mark's Square, everything seemed normal. Tourists took selfies, pigeons pecked at crumbs, and the Clock Tower showed the correct time. But Emma noticed something different.

The water in the canals was clearer than before. She could see all the way to the bottom, where strange clockwork machines moved slowly, keeping the city afloat.

As she sat on the steps of the square, catching her breath, a familiar figure approached. It was the man from the train, but he looked different now. His coat was dry, and he carried an old leather case.

"You're doing better than I expected," he said, sitting down beside her. "But you need to know the truth about your grandfather."

He opened the case, revealing a collection of old photographs. In one, her grandfather stood with a group of people in front of the Prague Astronomical Clock. They all wore the same symbol - a clock with thirteen numbers.

"Your grandfather wasn't just a clockmaker," the man said. "He was part of a group that tried to fix time itself. But something went wrong, and now it's up to you to finish what he started."

Emma's watch showed 20 days left. The ticking was louder now, almost urgent. She looked at the third key in the box - this one shaped like a lion.

As the man walked away, he left behind a single word: "Prague."

Emma knew her journey was far from over. The box in her hands felt heavier than ever, and the weight of her grandfather's legacy pressed down on her shoulders.

But as she looked at the clear water of the canals, she felt a spark of hope. Maybe, just maybe, she could fix what was broken.