Tamora arrives at Titus's house disguised as "Revenge" and claiming to want to help Titus "right his heinous wrongs."
Titus knows it's Tamora but plays along with her little game. He takes one look at Demetrius and Chiron and is all "Oh, I see you have brought 'Rape' and 'Murder' along with you. Gee, they sure do look like the Empress's sons. Come to think of it, you look a lot like Tamora."
Tamora thinks she's fooled Titus and pats herself on the back for being so clever. Then she asks Titus to bring his son Lucius home so she can have a little chat with him over dinner. She'll bring the emperor and his family so Titus can get his revenge.
Titus convinces "Revenge" (a.k.a. Tamora) to leave Demetrius and Chiron (a.k.a. "Rape" and "Murder") behind.
Titus tells the audience that, even though it looks like he's crazy, he's not.
Publius, Caius, and Valentine show up. Titus orders them to tie up Demetrius and Chiron and then gag them so they can't talk. (How fitting that Chiron and Demetrius are silenced. Isn't that what they did to Lavinia?)
Titus goes into another room, then reemerges with his daughter and a big knife. He declares that Chiron and Demetrius are about to pay for what they've done to his family.
Titus announces that he's going to make a tasty human pie out of Demetrius and Chiron and then he's going to feed it to their mom.
Titus slits their throats while Lavinia catches the blood in a big bowl.