Detectives Joe Cotton and Bill Thompson are asked by their superiors at the National Crime Authority, the UK's leading law enforcement agency, to investigate six murders that have been committed around England and Wales. Could the killer be a long-distance lorry driver or a traveling salesman? The killer murders his victims by spraying builders' foam down their airways and suffocating them in the most excruciating manner.

Will DI Thompson and DS Cotton solve this perplexing case, or will the killer strike again?