DCI Mark Lapslie's anonymous email bears a strange subject line: 'You Need To Listen To This.' He hears a woman scream - she screams twenty-seven times before her final death rattle is heard ... Lapslie investigates and discovers that the message was sent from the hospital where his new girlfriend works and where he's undergoing treatment for his synaesthesia - a neurological condition that confuses his senses so he tastes sound. Who is screaming? And why? Meanwhile, a murder victim has been brutally tortured and dumped on an island in the Thames Estuary. Then, a case is brought against him after questioning a minor and he's taken off the investigation. Unable to work, Lapslie must sit around, while the killer comes far too close to home ...