After Hester is returned to her cell, she is frantic and restless, prompting Master Brackett, the jailer, to summon a physician. The physician enters calmly, introducing himself as Roger Chillingworth, a man skilled in Christian medicine and native herbal knowledge. He is not a prisoner for a crime but is being held until the magistrates negotiate his ransom with Indian sagamores. Upon entering, Hester becomes silent as death, while her infant continues to moan in pain.

Chillingworth first attends to the infant, who is suffering severe convulsions. He removes a leather case, mixes an herbal preparation (derived from alchemical studies and Native American simples) with water, and offers it to Hester to give to the child. Hester refuses, fearing the doctor would harm the baby. Chillingworth calmly takes the infant himself and administers the draught, which quickly soothes the child's anguish and induces a deep sleep.

He then examines Hester, feeling her pulse and gazing into her eyes with a cold, familiar intensity. He offers her another herbal concoction, claiming it will calm her turbulent passions. Hester hesitates, expressing a wish for death, but ultimately drinks the potion at Chillingworth’s urging. As he does so, he places his finger on the scarlet letter on her chest, smiling at the symbolic burn.

While Hester drinks, Chillingworth delivers a lengthy monologue revealing his background as a scholarly, decaying man who spent years in the forest learning from Indians. He admits that his arrival in the settlement was driven by the sight of Hester with the scarlet “A,” and he confesses that he is, in fact, Hester’s husband, though he has concealed this identity. He speaks of his folly, his desire for intellectual mastery, and his vengeful resolve to discover the man who fathered Hester’s child. He vows to uncover the lover’s identity without exposing it to the world, promising not to interfere with divine justice but to keep the secret for himself.

Hester, terrified and confused, questions his motives. Chillingworth assures her he harbors no vengeance toward the innocent infant and that his medicines are for her benefit. He extracts an oath from Hester to keep his secret—both his identity and the identity of her lover—under penalty of danger to the lover’s life and reputation. Hester swears the oath.

Finally, Chillingworth departs, leaving Hester alone with her sleeping child and the scarlet letter, smiling ominously as he asks if she fears nightmares, hinting at his lingering menace.