After the seed-vault door seals itself with three slow knocks, Fern opens the unnumbered envelope she found and reads a note in her grandmother Judyth's hand: the first bed of the garden never had a number, and it lies buried under the poured floor of Main Aisle 40. With Wren she breaks through to a dry cellar - the buried Mother Bed - guarded by the warm ghost of the founding keeper, Mabel Heron, who did not die with an unfinished promise but sealed herself in to keep the founding seed safe for an honest steward. Fern reads the founder's letter, plants the pale founding seed with the trowel and watering can, and a night-bloom rises. Mabel, satisfied, hands Fern the master key before fading. Cliffhanger: a rank of hundreds of numbered doors now stands slightly ajar along the Spine Corridor's far wall, and the blank brass tag in Fern's hand slowly impresses the numeral 05 under her thumb.