Good detective work allowed the pair to arrest and charge a fellow policeman, who murdered an undercover officer in an attempt to keep a crook-police racket secret. But their work is not yet done. Who ordered the execution? Why? Just how high did the conspiracy go? And - and most importantly - does the crooked power group behind the assassin still flourish? There are questions that remain to be answered - so when the home office decides to reopen the case, it is Harpur and Iles to whom the investigation is once more handed.