The shooting of a man in a taxi at Hyde Park Corner appeared to be just another event in the bizarre catalogue of crimes with which London's detectives are painfully familiar.
A separate crime -- a murder which took place five years previously -- assumes increasing importance in the investigation and before long Fox is convinced there is a link between the killings.
Using his current girlfriend as bait, Fox attempts to trap the killer, but the plan goes disastrously wrong and Fox is left to face one of the most difficult problems of his career.
But throughout the investigation, Fox treats police regulations -- and the law -- with his usual disdain in successfully wrapping up the case, although this time not quite in the way he wanted...