Mara Venn used to measure streets before the sea took them. Now she works the night ferries of Bellwether, a city of roofline bridges, sealed lower floors, and neighborhoods that vanish twice a day beneath black-green water. She trusts gauges, anchors, and charts. She does not trust rumors about the Glass Tide, the rare hour when reflections show people who should not be there. Then an old almanac arrives in her father’s lockbox, its salt-stiff pages annotated in her brother’s handwriting. Eli disappeared seven years ago during an evacuation that officially had no casualties. The city paid settlements, demolished records, and moved on. But the almanac predicts Eli’s reflection at low water, in a district no map admits still exists. To follow the tide, Mara must cross the city’s drowned underlevels with a disgraced archivist, a ferry mechanic who knows too much, and the suspicion that her family helped build the lie that swallowed Eli. Each reflected face offers a clue, but every answer changes the water around her, as if Bellwether itself is editing the past. The Glass Tide Almanac is a speculative mystery about climate, memory, and the cost of surviving by omission. It asks what remains of a city when its maps are wrong on purpose, and whether love can be recovered from a history designed to sink.