Hester plans to intercept Dimmesdale along a forest path as he returns to Boston on his way back from visiting an apostle.
In the forest, in nature, Hester can be honest with Dimmesdale.
As Hester waits for Dimmesdale, Pearl asks to hear the story of the Black Man, a nickname for the devil. Pearl adds that the Black Man haunts the forest with a book that his converts must sign in blood. The Black Man then places a mark on his followers' bosoms.
Pearl's fascination with the Black Man is motivated by the secrets around the scarlet letter. In this way, suppression creates what is being suppressed.
Hester asks how Pearl heard this story and she responds that an old woman told her the Black Man put the scarlet letter on her mother. Eager to settle the matter, Hester confirms the false story of the letter's origin.
Like Dimmesdale's lie about his glove on the scaffold, Hester uses the devil to hide her sin.
Dimmesdale approaches. He appears weak, and walks with his hand over his heart, where Pearl suspects the Black Man has also left his mark.
Pearl has identified the link between her father's sin and her mother's sin.