Borderline

Undercover in Mexico, LA cop Madeleine (Claire Trevor) has helped a drunken thug (Don Diamond) back to his place, giving her the chance to search, when his drug smuggler boss Ritchie (Raymond Burr) shows up, followed by rival Macklin (Fred MacMurray, his first scene), in Borderline, 1950.

Neither "Macklin" (Fred MacMurray) nor Madeleine (Claire Trevor) knows that the other is an undercover cop looking to set up the same drug kingpin, posing as a married couple in a Mexican hotel, hitting some rom-com notes, in Borderline, 1950.

The head customs cop (Morris Ankrum) grills suspects (Peggy Converse, Clifton Young) about a drug smuggler with L-A cops (Howard Negley, Claire Trevor as "Madeleine") listening in, then offering an idea, hints of comedy, opening Borderline, 1950, with Fred MacMurray and Raymond Burr.