The next puzzle, "Platinum Clock," required assembling a 1,000-piece clockwork skyline. As she worked, the apartment’s analog clock began to tick backwards. The kettle on the stove wound itself down. Time, which had always been a steady companion, loosened like thread. A neighbor's muffled music rewound into silence, and a photograph in a frame on Mara’s shelf showed a face that changed with each pass of the puzzle pieces — older, younger, laughing, crying — as if the app adjusted the shutter speed of life.