The Scarlet Letter follows Hester Prynne, a woman living in Puritan New England who is publicly shamed after committing adultery. Forced to wear a scarlet letter "A" on her chest, Hester bears her punishment with quiet dignity while raising her daughter Pearl alone.

The father of Pearl is secretly Reverend Arthur Dimmesdale, a respected minister who hides his guilt while Hester is condemned openly. His internal torment contrasts with Hester's outward resilience, revealing the hypocrisy of a society that punishes visible sin while ignoring hidden wrongdoing.

Meanwhile, Hester's estranged husband, Roger Chillingworth, returns in disguise and devotes himself to psychologically tormenting Dimmesdale in revenge. His obsession consumes him, turning him into a symbol of how vengeance corrupts the soul.

Over time, Hester transforms her shame into strength through compassion and service to others. Her scarlet letter, once meaning "Adulteress," gradually comes to signify "Able." Dimmesdale eventually confesses his sin publicly before dying in peace, while Chillingworth withers away without his hatred to sustain him.

In the end, Hester chooses to continue wearing the scarlet letter—not out of punishment, but as a mark of her identity. The novel explores themes of public shame versus private guilt, justice versus mercy, and the power of redemption and inner strength.