Original Sin transports viewers to the late 19th century Cuba, capturing a tumultuous tale amid the backdrop of Spanish rule. The narrative elegantly shifts back and forth, revealing a gripping sequence where a woman awaits her grim fate by garrote, recounting her story to a priest.
At the center of this drama is Luis Vargas, a prosperous Hispanic-Cuban businessman, who eagerly invites Julia Russell, an American, to sail to Cuba as his bride. However, upon her arrival, Julia is nothing like the glamorous photos she had previously sent. She confesses to Luis that she seeks more than just superficial admiration; hence, she deliberately used a picture of an ordinary woman. In a twist of fate, Luis has also misrepresented himself, portraying himself as a humble worker rather than revealing his status as a wealthy coffee magnate.
Their whirlwind romance leads to a hastily arranged wedding just hours after Julia's arrival. While Luis is swept away by love, Julia grapples with her own inner turmoil. In the meantime, her sister Emily grows increasingly anxious about Julia's well-being after not receiving word from her for an extended period. Luis insists that Julia reply to Emily’s letters to prevent any alarming suspicions.
As Luis strives to ensure Julia's happiness, he includes her in his business dealings, granting her full access to his finances. It soon becomes apparent that Julia has absconded with a significant portion of his wealth. In a desperate bid to locate his wife, Luis pairs up with detective Walter Downs, hired by Emily, who suspects Julia's true identity and fears for her safety. Walter discloses his unsettling belief that Julia is an impostor, possibly linked to a larger, sinister plot.
Luis's journey to find Julia leads to a shocking revelation: she is colluding with Walter. Believing in their love, Luis deceives Walter, but when the truth surfaces, chaos ensues, resulting in a confrontation where Luis shoots Walter. Julia coldly instructs Luis to secure their passage home, but as soon as he is gone, Walter reveals he had been shot with blanks.
Though Julia shows signs of affection for Luis, her allegiance to Walter holds her captive, forcing her to continue her deceit. In an act of desperate love, Luis swallows a poisoned drink meant for him, hoping to solidify their bond. As they flee together, Walter pursues them, leading to a climactic encounter at a train station where deceit, love, and betrayal collide.
In a tense showdown, with Walter threatening Julia's life, Luis bravely intervenes, shooting and wounding Walter, while Julia deals the final blow. The story takes a haunting turn as Julia concludes her tale in front of the priest and requests his prayer. The following day, guards arrive to take her to execution, only to find the priest disguised in her garments.
As the story comes full circle, Julia finds herself in Morocco, observing a card game. She weaves through the players—including the familiar figure of Luis—gratefully watching the game unfold, while he narrates the gripping saga of their shared history.
