Dedication and results have earned Detective Chief Inspector Ross Tanner the prestigious charge of the Special Murder Unit. But Tanner has a secret - he is suffering from a rare disorder that causes intermittent blindness and hallucinations. When his deputy, Detective Inspector Tully, deduces the nature of his debilitation an uneasy alliance is formed between them. She will be his eyes in return for his help in furthering her career. As Tanner's relationship with the world becomes increasingly fragile he realises he must trust not only his ambitious deputy but also his own newly-developed perceptions. Success and survival will depend on the use of all his senses as he discovers that there is more to murder than meets the eye.