Antony and Eros have returned to the palace, and Antony asks Eros if he can still see him. Eros doesn't understand the question, and so Antony explains; he describes himself as being like a shadow or a cloud, insubstantial yet taking on various shapes. He seems to be only a mere shadow of his former self because of his defeat by Caesar and because of what he assumes to be Cleopatra's treachery.
Mardian enters and tells Antony that Cleopatra ("My mistress [who] loved thee") is dead, and that the last words that she spoke were "Antony! most noble Antony!" Antony is horribly shocked and instantly regrets his mistrust of her. He vows that he too will end his life. He calls Eros and commands him to kill him. Eros hesitates, and Antony pleads with him, saying that surely Eros would not wish to see him a captive of Caesar, defeated and shamed. Eros agrees, and he asks Antony to turn the other way so that he will not see Eros's sword. Antony does so, and Eros kills himself instead, after saying farewell to Antony.
Antony, both abashed and impressed by Eros's courage and loyalty, follows his example and attempts to kill himself by falling upon his sword. Antony's sword, however, does not pierce him fatally. Hearing his cries, Dercetas and other soldiers enter, and although Antony begs them to kill him, no one will do so. Diomedes enters and finds Antony still alive. He tells Antony that Cleopatra has sent him word that she is, in fact, not dead — that she lives. He explains that Cleopatra had hoped to defuse his rage by sending him word of her death, but then she feared that he might take his life. Thus she has sent Diomedes to tell Antony the truth. Antony calls for his guards and tells them to take him to Cleopatra.
We now see the results of Antony's poor judgment and mistrust. Having believed that he had lost everything, he attempted to kill himself, learning too late that he acted too rashly. Cleopatra, not fully understanding the agony of her Roman lover, precipitated his death by her melodramatic, manipulative playacting. (If this play is the first Shakespearean play you have read, it may seem unreal that Antony takes so long to die; most people who stab themselves do not make long speeches about it. However, in opera and in Shakespeare's dramas, this is very often the case.)