Spain, 2020. When ex-pat fugitive Jack Cleland watches his girlfriend die, gunned down in a pursuit involving officer Cristina Sanchez Pradell, he promises to exact his revenge by destroying the policewoman. Cristina's aunt Ana has been deaf-blind for the entirety of her adult life: the victim of a rare condition named Usher Syndrome. Ana is the centre of Cristina's world - and of Cleland's cruel plan. John Mackenzie - an ingenious yet irascible Glaswegian investigator - is seconded to aid the Spanish authorities in their manhunt. He alone can silence Cleland before the fugitive has the last, bloody, word.