Rebus is forced to juggle two complex cases when an old friend approaches him to trace her son, who has disappeared, and a former colleague is killed in a freak accident, which asks the question - did he kill himself or was he murdered?

The motto of the Scottish kings - Nemo mi impune lacessit ("Don't Mess With Me") sets the tone for this story. It's payback time for DI John Rebus in his pact with the crime underlord Morris Gerald Cafferty for his finding the person who put Rebus' daughter in a life-threatening coma, the result of a hit-and-run accident. This time, it's Cafferty's illegitimate son who was "six-packed" and killed, and Cafferty is calling in his chips from Rebus.

Rebus has to cope with a backdrop of gun running, jailbreaks, left- and right-wing extremists, nationalists and other splinter groups who are spouting racist philosophies, and imported white-power fanatics who are perpetrating hate crimes.