Esther

King Xerxes of Persia married a second time to Esther, a Jewess.  Esther had a cousin called Mordecai.  Mordecai would often sit at the king's gates.

At one stage, Mordecai overheard a couple of people plotting to kill the king.  He passed on what he heard, and the assassins were arrested before their conspiracy could be executed.

At another stage, Haman, one of King Xerxes trusted ministers, who was quite vain, wanted to be honoured and the king granted him this.  Everybody would bow to Haman on that special day, except for Mordecai.  Haman felt angry at this, and wanted Mordecai executed for the offense.

This plot then grew bigger, as Haman's friends advised that the whole Jewish community could be penalised for the offense; not just Mordecai.  Mordecai managed to persuade the king on this idea.

Word was passed through to Esther, who worried about what she could do.  Nobody could approach the king except when the king calls for it, or grants permission.  However, Mordecai persuaded his cousin to try.

While Esther was contemplating this, King Xerxes had a restless night, and called for the chronicles of his kingdom to be read to him.  When he came to realise that Mordecai had not yet been honoured for the failed assassination attempt, the king asked Haman what he could do.  Haman's advise resulted in him running before Mordecai to bring him honour.

Esther later plucked up her courage, and when granted audience with the king, told him of her plight, if the plan to kill all the Jews would take place.  The king quickly reversed his previous edict, had Haman hanged, and granted the Jews the permission to defend themselves.

For more information:
http://en.wikipedia.org/wiki/Esther
Esther