American Paul Melkow came to science fiction very early - and became famous surprisingly quickly. His first major work, “The Ring of the Singularity,” was awarded the prestigious Locus Prize for best debut novel in 2009 and a whole bunch of lesser-known awards in the genre. However, even earlier, the story “The Walls of the Universe” by Paul Melkow was nominated for the highest SF awards - Hugo and Nebula 2006 - and received the Theodore Sturgeon Award. The walls between parallel realities are becoming thinner. An ordinary young guy from a provincial town in Ohio, John Rayburn, and his double from the neighboring universe, John the Primary, suddenly change places. Which of the twin guys brought the Rubik's Cube to another universe, and which infected new fellow citizens with pinball? In which universe, strictly speaking, Are you and I living? So far, John and Primary have no time for answers to difficult questions. They're just having fun. For now... Because very soon a mortal threat will loom over ALL parallel realities - and they will have no time for jokes at all...