In an army camp near Sardis, Brutus, Lucius, Lucilius, and other soldiers meet Titinius and Pindarus. Brutus talks with the others about a disagreement with Cassius. Aside, Brutus tells Lucilius that Cassius is starting to seem fake and overly courteous, and that he doesn't trust him like he used to.
Suspicion is growing between Brutus and Cassius. Whereas in their earlier exchange, Cassius accused Brutus of being aloof and distant, now Brutus suspects Cassius’s excessive politeness as a front for his underlying disloyalty.
Cassius arrives and accuses Brutus of having done him wrong. Brutus, surprised, says that he doesn’t even wrong his enemies, so how could he wrong a “brother”? Cassius reacts impatiently. They withdraw to Brutus’s tent so that the army won’t overhear their argument. Lucilius and Titinius stand guard.
Cassius seems annoyed by Brutus’s outward show of innocence and nobility, a further sign of deteriorating trust between the men. They try to keep their conflict out of public sight.