Based on the first of the 'Boysie Oakes' novels by John Gardner, published in 1964. There were seven more: Understrike (1965), Amber Nine (1966), Madrigal (1968) Founder Member (1969), The Airline Pirates (1970), Traitor's Exit (1970) and Killer for a Song (1975). After that, Gardner took over writing the James Bond series from the late Ian Fleming.
The title song was sung by Shirley Bassey who had recently sung the title song for the James Bond film Goldfinger (1964).
This 1960's spy movie features a black-and-white opening sequence, something the James Bond film franchise would not do until Casino Royale (2006).
Composer Lalo Schifrin intentionally composed the score so it would not emulate John Barry's style from the James Bond franchise.
MGM originally planned a series of Boysie Oakes spy pictures, but this fell through.