Esther 7: 7-10
7 The king rose from the feast in wrath and went into the palace garden, but Haman stayed to beg his life from Queen Esther, for he saw that the king had determined to destroy him. 8 When the king returned from the palace garden to the banquet hall, Haman had thrown himself on the couch where Esther was reclining; and the king said, “Will he even assault the queen in my presence, in my own house?” As the words left the mouth of the king, they covered Haman’s face. 9 Then Harbona, one of the eunuchs in attendance on the king, said, “Look, the very gallows that Haman has prepared for Mordecai, whose word saved the king, stands at Haman’s house, fifty cubits high.” And the king said, “Hang him on that.” 10 So they hanged Haman on the gallows that he had prepared for Mordecai. Then the anger of the king abated.
There is a scene in the 1990s movie Pretty Woman, at the end where the Philip Stukey, the character played by Jason Alexander attacks Vivian, the main character played by Julia Roberts, causing the Edward, the protagonist played by Richard Gere, to throw out his main advisor. A similar thing is happening here. The king storms out, furious (even though he is at least partially to blame for the circumstance), Haman realizes the game is up and his only chance at mercy is not from the king, but the queen and he throws himself at her at the time the king returns and a convenient solution is presented. Haman has assaulted the queen, that allows the king to act immediately and the attendants (silent throughout the scene) now suddenly appear visible. Haman moves from favored one to traitor to death in the span of three terse verses. Ultimately it is the designs of his own hatred that end up being the mechanism for his own execution.
The book of Esther is a story set in a world where the death penalty is not only acceptable, but used not just for murder. Some people critique Esther for not extending mercy, which is their right, but that misses the context of the story and what was considered just punishment. Even if Esther wanted to extend mercy to Haman, and I see little reason to believe she would be inclined to, she may feel that she has pushed the benevolence of the king to its limit asking for the salvation of her life and people. The story turns on poetic justice, but I don’t think we need to make this prescriptive for the justice we seek in our own society.