Gentlemen Prefer Blondes (1953)

Lorelei Lee (Marilyn Monroe) is a beautiful showgirl engaged to be married to the wealthy Gus Esmond (Tommy Noonan), much to the disapproval of Gus' rich father, Esmond Sr., who thinks that Lorelei is just after his money. When Lorelei goes on a cruise accompanied only by her best friend, Dorothy Shaw (Jane Russell), Esmond Sr. hires Ernie Malone (Elliott Reid), a private detective, to follow her and report any questionable behavior that would disqualify her from the marriage.