Daniel J. Campion, in the employ of the Pickpocket Squad for the New York Police Department for many years, relates his experiences from the stage of novice rookie cop to top-notch detective. The skillful detective is a person whose most valuable instrument is his brain rather than his brawn. He must be able to size up a situation and detect events which are not congruous with the whole event. If a crowd at the zoo is watching the seals and one man is watching the crowd, this incongruity should alert the detective. After the crook is apprehended, the detective must recognize that crooks are human too and appeal to his reason and emotion if he wishes to extort additional information about buddies and previous crimes. Treating the crook decently often has advantageous consequences. The cop, on the other hand, if he wishes to maintain his integrity, must not be subject to the many bribes and pressures generated by political influence. The book is written in a very personal and colloquial style which may appeal to lay readers of law and crime.