Arriving on the eve of the annual colonial celebration of Fiestas de San Pablo, Lucky Gagin (Robert Montgomery) is a disaffected veteran on a mission to avenge the death of best pal Shorty. He enters a village divided by ancient class structures where Spanish heritage is valuable and the indigenous are only worth their white market value. A stranger in a strange land, Gagin heads for the posh La Fonda hotel where he's told there's no room for him. Snubbed and harboring his own prejudices, Gagin must rely on the kindness of the local proletariat to snake his way to war profiteer mobster Frank Hugo (Fred Clark). Aided by a mystical indigenous girl that accompanies him to an antique merry-go-round run by gregarious mestizo Pancho (Thomas Gomez, nominated for a Best Supporting Actor Oscar for the role), Gagin's biases soften amidst his new friends who unwittingly shelter him as he readies to strike.
Produced and co-adapted by Joan Harrison, who-by the filming of RIDE THE PINK HORSE-had established her reputation co-writing a number of key Alfred Hitchcock films. Harrison was one of the few female producers of her generation.