When FBI Agent Zack Stewart is killed, Agent John Ripley takes over the three cases he was working on, hoping one will lead to his killer. The first involves gangster Joe Walpo and Ripley finds his hideout through Joe's girl friend, Connie Anderson. Joe is killed but it is established he was 400 miles away when Stewart was murdered. The next involves a car-theft gang which Ripley breaks up by using one of the gang, Vince Angelino and his wife Julie. The last case involves Kate Martell, the victim of an extortionist who threatens to kidnap her child unless she pays him $10,000.
This certainly is an interesting look at FBI cases and procedures, with them using bulky equipment to spy on neighbors, intercept phone calls and make identifications. But this was the 1950s, when such things were primitive and relatively innocent. (The FBI surveillance went too far in the 1960s and was shut down by the courts.) Very interesting film, well worth being better known. And the film quality seems to have held up very nicely over the years. The one on Netflix looks great.