Season 1 · Episode 0

What came before Episode 1, at two different distances. Four years back: before Elvira ever took up the Marsh Causeway outpost, her household cat chose exile over a garden gate — and found, on a bare tidal rock, the first confirmation that her sensitivity to the boundary was real. Thirty-eight years back: a long-voyage ship stops answering, three machines are sent to it, and what they carry out are children. Twelve years back: the Survey Corps' first party on the membrane later registered as Counterpane logs nothing wrong for ninety days, and then a routine calibration returns a residual that will not close, and a Krenyi Section Lead files what happened and nothing smaller.

• S01E00C00 Below the BellsDún Rí, Terrace Garden — Road to the Old River AbbeyWeeks before the cat chooses the garden gate over the terrace, a second visit to Brother Daire's abbey on the Boyne gives both Elvira and Aldera their first taste of something the Fellowship's incense and chanting were never going to explain.
• S01E00C01 The Garden GateDún Rí, Terrace GardenThe autumn before Elvira ever reaches the Marsh Causeway, her household cat chooses the garden gate over the terrace — and does not come back.
• S01E00C02 What the Stones ConfirmedDún Rí, Household SanctumElvira's first attempt at a working of her own — one winter before chalk, thread, and the Marsh Causeway — produces one confirmed reading and no comfort at all.
• S01E00C03 Carraig BánCarraig Bán, an unnamed tidal islandPut ashore hungry on a bare rock, Aldera meets the first constraint-literate mind she has ever encountered that isn't human — and writes her first log entry.
• S01E00C04 A Person's NameAn unnamed long-voyage ship, deep transit — then Eden Space HabitatThree machines reach a ship that no longer answers. What they carry out are children — and within minutes of the carrying, one of the children makes a name that only she will ever use.
• S01E00C05 Survives CorrectionThe first party's shelter on the membrane later registered as Counterpane — then the Survey Corps Standards Office's calibration floor, EarthTwelve years before Threshold, the Survey Corps' first party on a newly reached membrane logs nothing wrong for ninety days, and then a routine correlation calibration returns a residual that will not close. Section Lead Syra applies every correction anyone can predict, files three words, and declines a softer one. At home, on a floor that never left, a Science Corps Principal rebuilds the bench to prove the instruments wrong, and finds instead what the record had only ever claimed for here.