Every evening, Mira sat on the underpass steps and played the same eleven notes. She never named the tune. It just showed up in her fingers one cold winter and stayed. Coins dropped into her open case while she played. But tonight a padded envelope was already waiting on the step. The address was written in her own slanted handwriting, even though she had never mailed a thing in her life.

Mira tore the envelope open. Inside was a single folded page covered in music notes, with one line written at the top: 'Play it backward.' The notes were her eleven, but flipped end to end. Her hands went cold. She set the page on her knee and picked up her instrument.

She refused to play it. Instead she read the rest of the page. Below the notes, in her own handwriting, were the words: 'You sent this to yourself. You just haven't done it yet.' Mira's mouth went dry. Somewhere a clock started chiming, far more times than it should.

The chiming stopped. Mira pulled out her phone and saw the date read three years in the past, the same winter the tune first arrived. A message sat on the screen, unsent, written by her: 'Tell yourself the notes are real.' She hit send before she could stop herself, and the cold winter air swallowed her whole.