Joe Bascom [Lou Costello] tails the slick con man Harry Lambert [Bud Abbott] all the way to Mexico City after a sunken oil stock scam back in the United States. Joe’s ex-girlfriend Mary [Virginia Grey], now going by the name Montana, has hired Lambert as her agent and passes herself off as a daring toreador. When Joe confronts Lambert at a bustling bullring, he also spots Mary in the ring, just as Amigo Americana Week is about to crown a goodwill ambassador by tossing a hat into the crowd. Mary, however, aims the hat at the crowd with a fiery swat intended for Joe, not for a random winner, and the moment hardens the tension between past romance and current schemes.
Joe is drawn back into the scam world, now playing the part of the “goodwill ambassador” while American authorities close in on him for the oil stock affair. He is using the alias Humphrey Fish while in Mexico, a detail that heightens the danger and the farce. The plan is kept alive by Lambert, Dagmar [Luba Malina], and Mary, who try to push fake silver mine stock on unsuspecting buyers. To lend credibility, Joe leads tours of the so‑called mine, praising its supposed natural beauty and engaging with visitors long enough to push them into buy-in. The scam’s momentum builds as more people are drawn in, and the comedy of errors accelerates.
Yet the authorities catch up with the trio, and Joe and Harry land behind bars. A last‑minute escape sees Joe disguising himself as an elderly Mexican woman, enabling his flight and letting him play a pivotal role in freeing Lambert. The chase leads them back to the bullring, where Dagmar has hidden the money needed for the stock plot inside her hat. In a tense moment of misdirection, Dagmar lucks out by tossing the hat—money in disguise—toward Joe as the bull nips at him, turning the arena into a chaotic stage for their final gambit.
Harry dives into the ring to retrieve the hat, while Joe—the still‑on‑the‑run goodwill ambassador—continues to dodge the bull’s charges. In a flurry of deft moves and narrow escapes, the funds are recovered and handed over to the authorities, effectively clearing the silver mine scam for the time being. Dagmar steps forward to make reparations for the related charges, ensuring their complicity is addressed, and the group finally sees a path home.
Overall, the caper blends sharp wit, quick disguises, and a hectic chase through a festive Mexican setting. The story remains faithful to its core: a crew scrambling to pull off a fraudulent scheme, a chase that zigzags from a bullring to a border town, and a finale that mends financial fences while leaving the door open for accountability back in the States. The dynamic between the leads—mistrust, grudging teamwork, and grudging respect—drives a plot that is equal parts slapstick and sleuthing, anchored by a memorable cast and a sequence of escalating set pieces.
