The creator of 'Silent Witness' and 'New Tricks' introduces DCI Mark Lapslie who suffers from synaesthesia, a neurological condition that 'cross-wires' his senses, providing simultaneously his greatest strength and his gravest liability. DCI Lapslie's investigations put him on the trail of a serial killer who, it soon becomes clear, has struck again and again, stealing each victim’s identity and possessions.