Curtis makes his move first. After trying to call Lewis, he heads to O’Connor’s apartment, where he’s greeted by the sickening smell of the man’s rotting corpse still laying in the recliner. He also finds the bomb-making equipment — and Lewis himself! Ever the good guy, Curtis tells Lewis it’s not too late to give this up and do the right thing. But Lewis, his mind twisted by trauma and disappointment, says he’s already doing the right thing. He’s in that scary place where someone does something awful, and instead of backtracking decides to justify their action by committing even more heinous acts. He and Curtis start fighting, and at first it looks like the older man has the advantage, but as we’ve seen already, Lewis is a brutal fighter with animal cunning. He eventually takes advantage of Curtis’ prosthetic leg, pulling it off and savagely beating his would-be mentor with it. It’s intense.
Quick note about Dinah, since we mostly see her in this episode hanging out with Billy (before she sparks the beginning of an alliance with Micro): I really hate this relationship. Billy is so obviously, cartoonishly evil, and he killed Sam. I think it really undermines Dinah’s character to have her fall head-over-heels in love with him because he has a nice beard or whatever. Some investigator she is.
Frank has an intense desire to hunt Lewis down himself. He says it’s to protect Karen, but I suspect he does see some of himself in Lewis, and fears it. So when he makes his way to O’Connor’s apartment and finds Curtis beaten, bloody, and tied to a bomb, he decides to take a different approach than his usual killing. He tries negotiating with Lewis — but then again, he doesn’t have much choice, since Lewis is on the opposite rooftop with a sniper rifle. Lewis says that Frank should be on his side, but Frank’s not having it. The Punisher isn’t motivated by grand ideology or paranoid conspiracy theories; he’s dedicated to protecting the people closest to him. So even if he and Lewis might have the same theoretical enemies, right now Lewis is threatening Curtis and Karen, and Frank will not accept that. After some intense back-and-forth, Frank convinces Lewis to tell him how to defuse the bomb.
But before he did that, Lewis called the cops. As he makes his escape, Frank must as well. The Punisher manages to hijack a cop car without killing anyone, but unfortunately he’s caught on the dashboard camera. Now everyone knows Frank Castle is alive.