For residents on the idyllic South Seas island of Pago Pago, life is simple until a boat arrives carrying two couples, the Davidsons (who are missionaries) and the MacPhails; and a prostitute named Sadie Thompson. Davidson is more than just a religious zealot; he's a madman. When the boat, which was en route to another port, is temporarily stranded on the island due to a possible Cholera outbreak on-board, Sadie spends her time "partying" with the American soldiers stationed on the island. Her behavior is more than the Davidsons can stand, and Mr. Davidson confronts her about her evil ways and offers salvation. When she rebels and the attempted redemption does not go as planned, Davidson arranges to have her sent back to San Francisco, where she fled some years ago because of mysterious personal issues. Davidson soon becomes unhinged, starting a series of surprising events that culminate in disaster.