A glitch at the sorting facility assigns a new postal code that routes mail between parallel worlds. Letters meant for 1407 in this world reach 1407 elsewhere. At first, recipients are confused: postcards from unfamiliar cousins, bills in currencies that sparkle. Claire receives a letter addressed to her from another Claire. It contains advice: "Do not take the job offer on Tuesday. Trust the violin." Claire, an accountant who quit violin years ago, is unsettled. She ignores the note. Tuesday arrives; the job offer comes with a move and more money. She accepts. Weeks later, she hears street musicians and feels an ache.
She writes back, apologizing. The postal service catches on to the code glitch and tries to shut it down. People protest; they like hearing from counterparts. Government fears cross-world contamination. Underground mail routes form. Claire receives another letter: "It is not too late. Music waits." She dusts off her violin, fingers stiff. She plays quietly, feeling something align. The job is fine, but music fills a gap. The postal code is officially retired, but mail keeps slipping through cracks. Claire volunteers at a community center, teaching violin to kids. She writes to her other self about the joy of small concerts. Somewhere, another Claire smiles, envelope in hand. The glitch becomes folklore, a reminder that sometimes the person who knows you best is the one who made the opposite choice.
Years later, Claire finds an old envelope at a yard sale, stamped with the forbidden code. Inside is a photo of a stage with her face on a poster—another world's version of her. She frames it. When she teaches kids, she tells them about the parallel postal system, not as proof of regret, but as evidence that paths diverge and still lead to music. The postal service quietly keeps one sorting machine unplugged, just in case the worlds want to write again.