We are welcomed to the action of the play in the year 29BC when it is believed that Octavian has murdered King Herod the Great. His wife, Mariam, soliloquizes about her husband's death; although it is unconfirmed she believes it is the most likely outcome of his visit to Rome. She loves Herod, and knows he loves her, but she also harbors resentment towards him because he had her grandfather and brother killed so that nobody would stand between him and the throne in the line of succession. Her mother, Alexandra, is not in the least conflicted and rejoices in his probable death. This is not a happily extended family; Salome, Herod's sister, never liked Mariam, and accuses her of being unfaithful to Herod. This seems to be a case of the pot calling the kettle black because Salome is planning to divorce her husband, Constabarus, so that she can be with her lover Prince Silleus of Arabia.
When Constabarus challenges Salome about her infidelity she tells him that she is going to seek a divorce. This is groundbreaking for the time because only men could seek a divorce.
Pheroras, Herod's brother, is then introduced. Before Herod died he was obligated to take the hand of Herod's infant daughter in marriage once she comes of age. Now Herod is presumed dead, he believes his situation has changed. Like many other characters, he, too, is conflicted about Herod's death; he loves his brother but his death frees Pheroras from the engagement, and now he is able to marry the woman he really loves, Graphina.
Constabarus has been hiding Barabas' sons who were sentenced to death by Herod twelve years previously. They belieive his death means that it is safe for them to come out of hiding but Constabarus wants them to remain in hiding at least until the death is confirmed, for their own safety. Meanwhile, Constabarus is challenged to a duel by Silleus with Salome as the "prize". Constabarus wounds Silleus, not fatally, but seriously enough for him to concede. Constabarus feels sorry for the Arabian prince and believes he is being used by Salome.
Salome, meanwhile, has heard about Pheroras' decision to marry Graphina. She is unhappy because she doesn't think Graphina is worthy of him. This is a pattern with Salome as she believes nobody is ever good enough for her brothers.
Rumors of Herod's death have been greatly exaggerated; he is alive, and this provokes a variety of different reactions from those around him Salome is delighted, but Pheroras does not share her joy because he has already directly disobeyed Herod's instructions and married Graphina, which is likely to provoke punishment. Salome goes ahead with her plan to get a divorce, and promises Pheroras that if he helps her she will speak to Herod on his behalf. She also shares her plan to get rid of Mariam by telling Herod his wife is trying to poison him. For her part, Mariam is not as conflicted about Herod as she was when she heard about his death. On hearing he is still alive, she is worried and disappointed.
Herod, by contrast, is looking forward to returning to Mariam, whom he assumes is going to be welcoming. On his arrival, Pheroras tells him that he has married Graphina, which, as predicted, makes Herod visibly unhappy. Pheroras then tells him that Salome has divorced Constabarus because he has been hiding Barabas' sons. Herod orders their execution. His mood is not improved by the arrival of Mariam. Her countenance angers him, but she is not in a conciliatory frame of mind, berating him for his violence towards her relatives. When a butler tells him that the drink he has brought to him has been poisoned by Mariam, he orders that she be taken away and killed, but backs away from this a second later. Meanwhile the butler is remorseful that he has attempted to frame Mariam and admits that she was not poisoning her husband after all. He tells Herod that it is Salome who has been plotting against Mariam. This makes Herod waver more about having Mariam executed. Salome sees this, and tells him that Mariam has been having an affair. Herod orders Mariam's execution. However, after she has been killed he is extremely regretful and wishes that he had not listened to Salome. He laments his decision and is deeply devastated at her death.
