Partridge arrives to visit Tom, looking pale and sick.
Tom asks him what is the matter.
Partridge informs him: the woman who was just visiting Tom? "Mrs. Waters"?
She is, in point of fact—Jenny Jones, Tom's mother.
So Tom realizes that he has committed incest with his own mother.
(That's—pretty shocking, actually. Echoes of the Oedipus Complex, anybody?)
Tom (as you might expect) is horrified, and starts feeling guilty right away.
Partridge goes to look for Mrs. Waters but doesn't find her.
But Tom receives a letter from Mrs. Waters saying that she has just discovered something about Tom, and they have to talk.
She tells him not to freak out until they next meet.
She promises him in writing that Mr. Fitzpatrick is better, so at least Tom isn't guilty of murder.
Both Partridge and Tom read this letter and take it as confirmation that Mrs. Waters = Jenny Jones = Tom's mom.
Black George arrives at the prison.
Black George reports that there has been a big argument among the Westerns, and that Mrs. Western has left swearing that she will never speak to Squire Western again.
Squire Western has also promised Sophia that he will never lock her up again. (How nice of him.)
The narrator jumps in to explain why the Westerns have been fighting:
Mrs. Western tries again to force Squire Western to marry Sophia to Lord Fellamar.
Squire Western refuses, and the two siblings fight so violently that Mrs. Western storms out.
She totally forgets to show her brother Sophia's letter from Tom, which is lucky for Sophia.
Once Mrs. Western leaves, Sophia starts trash-talking her aunt to Squire Western.
Sophia has never sided with her father against Mrs. Western before.
He is so pleased to hear her turning against her aunt that he promises never to lock her up again.
Sophia swears that she will never marry a man without Squire Western's consent.