A Chinese spy in England during World War I must transmit a message before he is caught, and his solution involves a book that is also a labyrinth. Borges published this story in 1941, and it anticipated hypertext by decades, proposing a narrative that branches at every moment into all possible futures. The plot is detective fiction; the content is metaphysics. Time forks perpetually toward innumerable futures; in one of them, any outcome occurs. The story is brief, intricate, and vertiginous. It changed what fiction could think about. Every linked narrative descends from this garden.