“It’s May Fourth 1993 when you read this,” the manuscript’s tight, pinched script began. “If my calculations are correct, you’re in Grandma’s attic, reading this book, which you found when she sent you up there to look for a photo album. I know this because I’m you. And I – we – invent time travel. Everything you need to know is here, but you need to follow the instructions exactly. Step one: go to the Danby Bridge today at six o’clock.” Brow furrowed, Jeremy shouted down the narrow stairs, “Grandma! What day is it!?”

“The seventh! Why do you want to know?”