Private detective Jack Masters takes on a case and gets mixed up in murder, sex and blackmail.
Production
Made for pocket change before Rocky; looks like it.
Acting
Allen Garfield commits to sleaze with uncomfortable dedication.

Director
John G. Avildsen
Trivia, insights & behind the scenes
Avildsen disowned this film so thoroughly it's nearly impossible to find legally; he reportedly paid to suppress it after Rocky made him bankable.
This exists in the brief window between the collapse of the Hays Code and the rise of hardcore porn, when 'mainstream' sex comedies could still titillate without showing everything.