This book is set during the time of the Persian empire. It begins with an account of King Ahausuerus. In his third year, he holds a grand celebration that highlights his wealth and power. In the midst of this festival, he calls for his queen, Queen Vashti, to be brought before him. He wants to show off her beauty. She refuses to come which starts a chain reaction that leads to a decree that banishes Queen Vashti from his presence and seeks to assert a mandate upon all women in the empire to honor their husbands.
After the banishment, a decision is made to seek out all the most beautiful virgins to create a group of women for Ahausuerus to pick a new queen from. A beautiful Jewess named Esther who is among the Jewish exiles living in Persia is taken as one of these virgins. Esther is being raised by her uncle Mordecai. Esther is chosen as queen, and after this, Mordecai becomes aware of a plot to harm the king, and Mordecai warns Esther, who, in turn, warns the king. The evil men are captured and hung.
After this, a man named Haman rises in Ahausuerus's administration. He demands to be bowed to. Mordecai refuses and enrages Haman. This causes Haman to use his influence with the king to convince him that the Jews were a disruptive group of people in the kingdom. He convinced the king to issue an edict allowing Haman to wipe them out from throughout the Persian empire. Mordecai and many Jews throughout the empire tear their clothes and mourn upon learning of the edict. Mordecai crys out for Esther to intervene with the king. Esther informs Mordecai that if she approaches the king unbidden, she may lose her life, but Mordecai reminds her of her responsibility to the people. She commands Mordecai to gather with his friends and fast and pray for her safety. She also fasts and prays with her servants as she prepares to approach the king. After three days, she approaches the king, and he extends the scepter which signals his pardon of the breach of protocol by Esther. He makes it clear that her request will be granted..."even up to half the kingdom." Esther chooses to simply invite the king and Haman to a feast to be held the following day. Haman is ecstatic at this news because he takes this as a sign of great honor that he has been invited to a feast that will only be attended by the king and queen besides himself. As he is leaving, however, he passes Mordecai who once again refuses to bow. This infuriates Haman, and he is counseled by his friends to build a large gallows from which he can hang Mordecai. Haman does this.
Meanwhile, even as Haman is building the gallows, the king searches through the chronicles of memorable deeds. As he searches these records, he discovers the fact that Mordecai saved his life. Haman arrives just as the king is trying to decide how to honor Mordecai. As the king asks for ideas about how to honor Mordecai, Haman assumes he is referring to him. He is profoundly humbled as he is made to parade Mordecai around the city. As soon as he arrives home after this, Haman is summoned to Esther's feast. Esther reveals the desperate situation of her and the Jews at her feast. As the king becomes enraged, he demands to know who is responsible for these events. Esther points to Haman and identifies him as the culprit. The king leaves briefly in anger. Haman tries to beg for his life with Queen Esther, but the he trips and falls on her just as the king returns to the room. This further enrages the king, and Haman is hanged on the gallows he prepared for Mordecai. The same day this occurs the king gives the house of Haman to Esther, and Haman's position is given to Mordecai.
Esther pleads to the king for intervention on behalf of the Jews. The king gives Mordecai authority to issue a decree allowing the Jews to gather, defend themselves, and plunder their enemies on a certain day throughout the empire. The Jews carry out the edict and defeat their enemies. They do not partake of the plunder, however. The Jews in the capital city of Susa are even allowed a second day of killing their enemies. The day after their victory is made a regular day of celebration on the Jewish calendar. This is known as the Feast of Purim named after the term Pur which means to cast lots. Haman cast his lot against the Jews, and it was flipped on his head. His desire to destroy, destroyed him and became a blessing for the Jewish people. The book ends by making it clear that Mordecai becomes second in command to the king and continued to seek the welfare of his people.