Hester Prynne committed adultery with Arthur Dimmesdale, a minister of religion. Their illicit liaison took place while Hester's husband, who later returns as Roger Chillingworth, was far away from home. During this time, it was thought that he'd been killed by Native Americans. However, to the Puritans of Boston, this in no way excuses what Hester did. To them, the marriage bond is sacred and must always be respected, no matter what the circumstances.

When Hester's adultery is discovered, she is subjected to public humiliation before the people of Boston and forced to wear a scarlet letter "A" that identifies her as an adulteress—and, therefore, a non-person in this ultra-religious community. At the same time, no one other than Hester and Dimmesdale knows the identity of Hester's lover and the father of her child. Hester reveals nothing; she steadfastly refuses to give up her lover's identity, no matter how much pressure is put on her.

As for Dimmesdale, he's morally and spiritually tormented by his sinful actions. His feelings of self-loathing and worthlessness are only made worse when Chillingworth arrives on the scene and, having figured out that Dimmesdale is his wife's lover, proceeds to destroy him psychologically.