...Nicolas and Margaret have made it inside and locked themselves in one of the bedrooms. Nicolas advises her, while they have time, to write a note dated before her death that expresses suspicion that Jack was going to kill her, even describing how and when she "thought" he would do it. She thinks that's a great idea, and gets to work...

...even as Jack has busted into the house with the shovel...

...and back in the room, she's finishing off the note -- only she suddenly realizes that Jack, not knowing squat about horses, wouldn't have had the knowledge to use a masking agent, as the killer did. Nicolas starts to babble about how he could have found out that information from anyone, but eventually gives up the ghost (ooh, sorry) and produces a hypo, which I guess means he was going to kill his mother again as soon as she finished framing her husband. "Oh, Mother. You could never let things lie." There's an opening there for a witty rejoinder about his gambling losses, but given the circumstances I don't blame her for not making it.

Back from commercial (hey, they threw in an extra act break! Thanks, show!) Nicolas sneers that killing her the first time was difficult, but as he hangs around her more, he's getting more pleasure out of the idea. She tries to say she can understand why he drugged the horse -- so he could get out of his debt -- but he tells her that that was just a contingency plan in case it was all she left him. She realizes that means he was going to kill her no matter what, and even as Jack is banging on the door with the shovel, it looks like he's going to be too late, as Nicolas forces Margaret down onto the bed and makes to inject her. Hate to bring up such an obvious technical point here, but where is Echo's new handler? Bad, bad omission on the show's part, even if the guy is new. However, despite his incompetence, his charge doesn't die at this moment, as Jack smartly (although not believably, since we didn't see it when he came into the house nor when they showed him banging on the door like four seconds earlier) blows the lock off with a shotgun. He and Nicolas have an altercation that's a little rougher that you'd expect in a WASP estate, especially from guys who drink Long Island Iced Teas, but remember that Jack was a poor boy on the streets of Manila and Nicolas, as a degenerate gambler, can't exactly be a stranger to fistfights. Anyway, despite his bleeding gut wound, with a timely assist from Margaret, Jack gets the better of Nicolas, knocking him out, and then collapses sobbing on the bed. William then pops in, thankfully still conscious, and Margaret sends him off to call an ambulance and the police. When he's gone, she has the presence of mind to burn the note, and then Jack gasps that he hopes she never knew the truth about her son, as it would have killed her. Margaret: "It did." She drops the flaming paper in the wastebasket...