The Medusa Frequency — Russell Hoban

An inexplicable message flashed onto the screen of his Apple II computer at 3 a.m. heralds the beginning of a startling quest for frustrated author Herman Orff. Taking up the offer of a cure for writer's block leads him 'to those places in your head that you can't get to on your own' - and plunges him into a semi-dreamland inhabited by a bizarre combination of characters from myth and reality: the talking head of Orpheus; a lost love; the young girl of Vermeer's famous portrait - and a frequency of Medusas.