A mob bookkeeper is killed by hitman Cappy Gordon, Jack Palance, acting on orders from gangster Vic Spilato, who is currently under investigation by the U.S. Senate. Cappy then heads for the Latin American town of San Cristóbal with a ruthless plan to murder singer Clare Shepperd, Linda Darnell, the woman who is connected to Spilato in the past.
Meanwhile, American prizefighter Russ Lambert, Robert Mitchum, also makes his way to San Cristóbal to clear his mind after the unintended killing of an opponent in the ring. Clare, operating under the alias "Clare Sinclair," seeks out Felipe, Dan Seymour, a bar-owner who once had criminal ties to Spilato, and she sells him a valuable pair of earrings. Clare finds herself drawn to Lambert after she watches him defeat the local challenger Rivera, whom she had mistakenly backed in a bet.
Cappy eventually locates Clare and confesses a twisted love, promising to spare her life if she runs off with him. Instead, Clare escapes to Felipe's bar and threatens to expose the owner to Cappy unless Felipe can convince Lambert to meet her at the secluded Posado de Don Pascual. Felipe complies, and Clare and Lambert meet there, setting the stage for a romance that blossoms while Clare keeps her stormy history hidden from him.
The couple travels by an aerial tramway to La Cumbre, a secluded mountaintop village, strolling through the quiet streets while Cappy tails them. A provocative dance scene unfolds, watched by the pair, and the performance is interrupted when Vasco, the jealous husband, drags his partner away, kills her, and is arrested. The mood shifts to urgency as Clare and Lambert decide to stay at a hotel since the lift stops operating for the night, leaving them with limited options to leave La Cumbre. They share a quiet kiss, and Lambert reveals that he knows about Clare’s complicated past with Spilato.
Alone in her room, Clare faces a threat from Cappy, who demands a rendezvous on the cable car and threatens Lambert’s life if she refuses. To protect Lambert, Clare pretends to concede but slips away and heads toward the cable car. Lambert, realizing she’s in danger, follows and finds the car in use by local police to transport Vasco to San Cristóbal. Clare claims she has changed her mind and intends to end things with Lambert, but he remains unconvinced.
At an intermediate stop, Cappy again pressures Clare, who seems ready to leap into the void, but she faints and is carried back onto the car by Lambert as the journey continues. High above an abyss, one of the main cables snaps, jolting the car and killing the engineer as they swing into gravity’s pull. The stranded passengers face a deadly choice as the remaining cable begins to fray, threatening to plunge them all to the chasm. The options include swinging to a nearby cliff to trigger two rescue lifts, which can only carry a limited weight—meaning three people must be sacrificed if the second cable fails.
Vasco volunteers first, allowed by an officer who understands his young son is among the riders; he swings to the cliff and dies on impact. Lambert then volunteers and succeeds, returning with the first lift. Before Clare and the others can board, Cappy seizes a police handgun and wounds the officer, attempting to board the lift with Clare. Lambert intervenes, and a brutal struggle ensues. A single punch from Lambert sends Cappy tumbling over the railing to his death, while the remaining passengers scramble onto the lifts and withdraw to safety just moments before the cable parts and the doomed car hurtles into the abyss.
