Tree, will you please tell me what's going on? At first, I thought he was trying to kill...

[after Tree kills Tombs, she and Lori run away] Lori Spengler: Tree, will you please tell me what's going on? Tree Gelbman: At first, I thought he was trying to kill me, but it's you he's after. Lori Spengler: Who? [a person wearing a Bayfield Baby mask, armed with a knife, blocks their way. Tree, who has figured that person is the real murderer, points the gun at him] Tree Gelbman: It's over, Gregory! [the masked person removes the mask, revealing himself to be Dr. Gregory Butler] Lori Spengler: [shocked] What? Why? Tree Gelbman: His wife found out about your affair... [a flashback: Gregory and his wife arguing] Tree Gelbman: ...so he stole a page from your old playbook. He set Tombs free, knowing that everyone would think that he killed you... [a flashback: Tombs is transported to the OR. Gregory secretly places a Bayfield Baby mask on Tombs' face and a knife in his bed] Tree Gelbman: ...and the secret of your affair would die with you. [Gregory claps his hands mockingly while he keeps advancing toward Tree and Lori] Gregory Butler: Bravo. Well done, indeed. Tree Gelbman: [disdainfully] Once a douchebag, always a douchebag. Gregory Butler: I'm sorry, do I know you? Tree Gelbman: Stay back, asshole! [Gregory ignores the warning and keeps walking toward them. Tree shoots near Gregory's feet. He stops and drops the knife. At the lab, the guards keep trying to open the doors by force]