Cal & Alf. Callum & Alison. They were supposed to be part of each other’s lives forever, if only the universe had let things happen the way they should. But whoever they were before, they’re different people now, and the problem with living here is that is always pulls you back again, no matter how hard you try to get away. And the universe that sent them spinning into free-fall throws them together again when the girl who ran away comes back to find out what happened to the boy who didn’t want to leave. And the question that the universe needs to answer most of all now is – Whatever happens to those bits of us we leave behind and thought we’d lost forever?