The film's opening scene finds our anti-heroin, Susana (a wayward and salacious girl), incarcerated in a girls' reformatory, on her knees in prayer; appealing to God to deliver her from her frightening surrounds - and pointing out that it was, in fact, him who made her "the way she is". Her prayers are answered when, after being temporarily granted Herculean strength (or a spot of luck), she manages to bend the bars of her cell and escape into the rainy night. Susana eventually happens upon a horse ranch run by Don Guadalupe and his stand-up, catholic wife Dona Carmen. Her portentous arrival coincides with Guadalupe's favourite mare giving birth to a stillborn foal. Nonetheless, the flustered escapee is taken in and duly adopted as a surrogate daughter by Carmen. Susana's presence amongst the ranch-folk soon begins to become corrosive when, after learning of her escape from the reformatory, farmhand Jesus successfully bargains his silence in exchange for her 'company'. Lives are further unsettled when Susana begins to fall for both Don Guadalupe and his bookish son, Alberto. Susana's voracious and devilish nature eventually pushes Dona Carmen to breaking point as she frantically whips the "bitch of bad breeding" for "poisoning her family".