Four horticulturists answer a strange invitation: a once-in-fifteen-years orchid will bloom for a single night at a chateau above Dunwich, Massachusetts, on the last night of September, 1921. There is no orchid society. There is no host. Every invitation is written in the same hand. The bloom is a clock, and the house has been waiting a very long time for its guests. The Blooming is a complete horror one-shot for a game master and three to five players, about four hours at the table. It builds slowly: three quiet acts, a peak in the Master Suite, and no relief from the trapdoor onward. Use it with any horror system. Its checks come in three weights and its threats are described in plain words, and an appendix maps both onto your own rules. Inside: six acts and an epilogue, a guide to the house and its history, five pregenerated investigators, thirteen player handouts, four maps, and found documents. The book itself is haunted. A survivor of that night and a later reader have written in its margins, and the second hand grows less sane toward the last page. Come alone. Speak of it to no one. Content warning: body horror, pregnancy imagery, and an unwinnable ending. For mature readers.