Jack Kelly probably knew more about narcotics trafficking in America than any other person.  From the time he joined Atlantic City Police Department at the end of World War II to his retirement from one of the highest enforcement positions in the United States Bureau of Narcotics and Dangerous Drugs, Kelly spent his life in pursuit of the world's largest, most cunning, and dangerous illicit drug suppliers.  Along the way, he earned a reputation from peddlers and junkies, as well as federal and local law enforcement officials, as "the toughest narc of them all."

According to the book description, “On the Street is Jack Kelly's story.  It is also the story of drugs in America and of the people who become enmeshed in its widespread, complex network. As Kelly unfolds the story of his career, we learn what makes a good cop-and a bad one.  He discloses in considerable detail the psychology of developing informers and of keeping them; how suspects used to be-and are-interrogated; and how evidence is handled.  He shows how a set-up is arranged and an arrest made, and he tells what it's like to work undercover, as he did for much of his career, on numerous occasions almost losing his cover-and his life.

Kelly is brutally frank.  He tells not only of informers who, after being loaned money by agents to set up a purchase, run off with the loot, but also of policemen who, finding large quantities of cash at the site of an arrest, report only a small portion of it and pocket the rest.  He narrates with compassion the story of the elderly medical doctor who gave heroin to his junkie patients because he truly couldn't stand to see anyone suffer.  And he tells in sorrow of the narcotics agents who became junkies themselves.”