(Head up; this summary is going to be a long one. The narrator is trying to cram in all the (many) details we need to know from years of deception so that we can go forward with finishing up the plot of Tom Jones. In other words, this chapter is heavy on the exposition.Brace yourselves!)
The new arrival is Squire Western.
Squire Western comes in to speak to Squire Allworthy.
He complains (as usual) about Sophia.
Squire Allworthy reminds Squire Western that he had promised there would be no violence towards Sophia.
Squire Allworthy offers to talk to Sophia if Squire Western lets her out of her locked room.
Squire Western thanks him and agrees.
Squire Allworthy asks if Squire Western has seen Mr. Dowling recently? He needs to speak to him.
Squire Western answers that Mr. Dowling is still back at his place, sorting out his mortgage with Nightingale Senior.
Squire Allworthy plans to come over right away.
Squire Western takes off, and Squire Allworthy wraps up his conversation with Mrs. Waters.
She complains that she was tricked into running away with a man who planned to marry her but never quite made it legal.
She lived with him until he died twelve years later, and was always faithful to him.
Then, she took up with Captain Waters, and then with Tom (as we see in Book 9).
She swears that Tom is a good man, and that he has honestly decided to give up his bad habits.
Squire Allworthy promises that, if Mrs. Waters also gives up her immoral ways, he will financially support her.
Mr. Dowling enters the room.
He looks deeply uncomfortable when he sees Mrs. Waters (whom he still thinks is Mrs. Fitzpatrick).
He claims he has an appointment with Squire Western, but Squire Allworthy locks the door behind him.
Squire Western asks Mr. Dowling to be honest about what he discussed with Mrs. Waters.
Squire Allworthy promises that he'll forgive Mr. Dowling for anything he did under Mr. Blifil's orders.
So Mr. Dowling tells all: Mr. Blifil sent Mr. Dowling to Mrs. Waters/Fitzpatrick.
And Mr. Blifil also sent Mr. Dowling to the gang of witnesses.
Mr. Blifil claimed that it was Squire Allworthy who was so eager to see "the villain [Tom] brought to justice" (18.8.5).
So Mr. Dowling went to the witnesses to tell them that if the people from Tom's side tried to speak to them, they should stick to the truth and be honest.
And that honest truth (for which they are going to get paid by Mr. Blifil) is that Tom hit Mr. Fitzpatrick first.
Mr. Dowling repeats that he did all of this to please Squire Allworthy.
Squire Allworthy asks how Mr. Dowling could possibly have thought these corrupt actions against Tom would make him happy.
Mr. Dowling answers: "it did not become me to take any notice of what I thought you desired to conceal" (18.8.5).
Squire Allworthy understands what Mr. Dowling is hinting at: that Squire Allworthy might have wanted to get rid of Tom because Tom is his sister's bastard child.
Mr. Dowling confirms that he knows Tom's true parentage, since Bridget's last words were about her illegitimate son.
Squire Allworthy wants to know how this last message from Bridget never reached him.
Mr. Dowling answers: when he gave the news of Bridget's death, he was in a hurry, and Squire Allworthy had sent Mr. Blifil to speak to him.
So he gave Bridget's final letter to Mr. Blifil, as Squire Allworthy's representative.
(We can confirm that this whole exchange happened: it's right there in Book 5, Chapter 7: Squire Allworthy asks Mr. Blifil to talk to Mr. Dowling in his place, because he's too sick to leave his bed. We are impressed with Fielding's attention to continuity.)
Back then, Mr. Blifil bribed Mr. Dowling to keep quiet about Bridget's secret.
And since then, Mr. Dowling has just assumed that Squire Allworthy has been covering up for the sake of Bridget's reputation.
Squire Allworthy swears Mr. Dowling to silence about all of this and then takes him to the door.
He doesn't want Mr. Dowling to speak to Mr. Blifil on his way out.
At the door, Squire Allworthy meets Mrs. Miller.
He explains everything to her: Tom has been proved innocent, but Tom's apparent half-brother, Mr. Blifil, is a "wicked viper" (18.8.10).
Squire Allworthy now admits that Tom has been wronged all of this time.
Mrs. Miller thanks Mrs. Waters for being the one to clarify all of this to Squire Allworthy.
Mrs. Waters answers that Tom will be out of jail soon, since a doctor has gone to testify that Mr. Fitzpatrick is still alive.
Squire Allworthy looks forward to seeing Tom, but he has one more errand.
He starts arranging transportation to go out.
Mr. Blifil appears and asks Squire Allworthy where he's off to.
Squire Allworthy refuses to answer.
Just as he is leaving, Squire Allworthy suggests that Mr. Blifil find the letter his mother sent to Squire Allworthy on her deathbed (you know, the one that tells of Tom's real parentage!
We wish we could see Mr. Blifil's face when Squire Allworthy reveals that he knows all.)