A writer of 'mundane' or 'literary' fiction might use this incident as the beginning or end of a conventionally epiphanic short story. But what use is this sudden random intrusion of otherness to a science fiction writer? How to fit the inexplicable into the cosy metric frame of conventional sf stories, in which everything has its place, and all is transparent? It's something I've been wrestling with ever since I started writing my second novel, Secret Harmonies (Of The Fall, in the US), in which the tensions in an interstellar colony were laid bare by an inexplicable disappearance. I'm still wrestling with it more than twenty years later.