Second-billed Marilyn Monroe is the blonde in question in this second film version of Gentlemen Prefer Blondes: Miss Lorelei Lee, whose philosophy is "diamonds are a girl's best friend." Together with her best human friend Dorothy (top-billed Jane Russell), showgirl Lorelei embarks upon a boat trip to Paris, where she intends to marry millionaire Gus Esmond (Tommy Noonan). En route, the girls are bedeviled by private detective Malone (Elliot Reid), hired by Esmond's father (Taylor Holmes) to make certain that Lorelei isn't just another gold-digger. When Dorothy falls in love with the poverty-stricken Malone, Lorelei decides to find her pal a wealthier potential husband, and that's how she gets mixed up with flirtatious diamond merchant Sir Francis Beekman (Charles Coburn) and precocious youngster Henry Spofford III (George \"Foghorn\" Winslow). Most of the Leo Robin-Jule Styne songs from the Broadway show remain intact, including Marilyn Monroe's rendition of "Diamonds are a Girl's Best Friend," a production number later imitated by pop icon Madonna.