Brutus anxiously ponders joining the conspiracy against Caesar. When he is brought one of the unsigned letters that Cassius has had left for him to find, Brutus decides to act. Visited by the conspirators, he agrees to join them but rejects their plan to kill Mark Antony as well as Caesar. When the other conspirators have left, Portia, Brutus’s wife, begs of him an explanation for his sudden change of mood. Brutus, joined by Caius Ligarius, departs for Caesar’s.