'The wages of sin is death' - Romans 6, v 20-23. A middle-aged man, reported missing by his distraught wife, is found dead, brutally mutilated, on common land in south London. These ominous words, taken from the Bible, are found with his body. There are shocking similarities with another recent murder, in Gloucestershire. This is DS Matt Arnold's beat, and he is soon involved in the increasingly gruesome hunt for a serial killer. On the home front he has problems, too. His young son is in a coma, the victim of a hit-and-run accident, and Matt's wife, Jo, is barely speaking to him. Husband and wife both blame one another. As the investigation gathers pace and Matt spends more time at the station, the pressure on his family life becomes unbearable.