"There's got to be consequences."
Harry is fully out of himself now, he's a dog with a bone as we know him to be, and though it never helps him in the pursuit of healthy relationships, it certainly works in getting people rattled and getting them to confess to uncomfortable truths, I think in part because he makes lying more uncomfortable. He just can't seem to be able to accept the injustices of the world even if he has a more single-minded focus, instead of a bigger-picture one.
He follows Meg around and finds Percy's mom, we learn she was driven away by the family and she chose an easier life by just staying away, but she did say Percy run away, which leads Ambrose to learn of her time away from the family, which had a short-lived moment of peace but then she felt chased and went back. With a lot more information he decides to use Sonya to throw the Muldoons off and they invite them to dinner, which he makes super uncomfortable for everyone involved, but he does learn thanks to this that Percy's dad had a drug problem and it was him the one that was driving it that fateful night.
This probably lets Ambrose know that Percy likely did not come off that cliff alive, something that seems to be confirmed by the final shot in the episode, we don't see her face but I don't think this is the kind of show that would try to trick us like that. I have to say, though, there was barely any doubt in my mind that Percy was dead, which is why I'm not sure why they took so long to confirm that, I just don't see a good reason for it right now.
Lastly, I feel I have to mention Sonya, I know that knowing something and living it are two different things, but we're talking about someone that met Harry in one of his darker moments and she was drawn to that. Now she suddenly wants him to be a "well adjusted" person? Just in the last episode, she was saying she saw him come alive with the case, and now she's saying his ugly side has come out? I mean it's not impossible for a person to change their mind like this feels like a miss on the writers' part.
It seems to me like they're focused on showing that Harry's obsessive behavior always gets in the way of his happiness, something they've hammered us with again and again, but had no interest in making Sonya a truly fleshed-out character. I hope they're going in a more interesting direction with this because I honestly expect better from this show, but I guess we'll find out soon enough.
"I'm better on my own."