Marcia and Lucia speak in a chamber. Marcia explains she cannot be with Juba because of her father, but she does not want to be with Sempronius. “I like not that loud, boist’rous man,” she says (43). The two exit and Sempronius enters, disguised as Juba. He is soon met by the real Juba, however, and though Sempronius attempts to attack him, Juba stabs Sempronius first. “Am I then doom’d to fall / By a boy’s hand, disfigured in a vile / Numidian dress, and for a worthless woman?” Sempronius asks before he dies (44).

Juba exits and Marcia and Lucia enter, finding Sempronius’s body. Marcia mistakes it for Juba and mourns him, calling him the “best of men” (45). Juba overhears this and reveals himself, and Marcia admits that her “love […] has broke through all / Its weak restraints” and she cannot conceal it any longer (47). She leaves and wishes Juba well in war, telling him to “prosper in the paths of honour” so that his “virtue will excuse my passion for thee” (47). Juba resolves that his fate in battle does not matter as much to him as his fate with Marcia, saying, “Let Caesar have the world, if Marcia’s mine” (47).