Hester and Pearl plan to waylay Dimmesdale on his way back from visiting a sick person.
Pearl, who is really sassy for a Puritan child, teases her mom that the sun is afraid of the scarlet letter.
When they sit down to rest, Pearl asks for a story about the Black Man who haunts the forest and offers a book and iron pen to everybody who meets him in the trees. Anyone who encounters him has to write their name in the book in blood.
Apparently this is a common superstition, which Pearl overheard an old woman talking about.
The old woman claimed that lots of people had written their names in the Black Man's book, including Mistress Hibbins, and that the scarlet letter was the Black Man's mark on Hester.
So, mom, is that true?
It sure is. Hester has met the Black Man, and the scarlet letter is his mark.
When they meet Dimmesdale in the woods, Pearl asks whether he holds his hand over his heart because the Black Man had put his mark there.
And if he does have the Black Man's mark there, why doesn't he wear it on his clothes, as Hester does?
Hester tells Pearl to take a chill pill, and looks at poor Dimmesdale, who's looking pretty rough.