Yeats`s one-act verse play Deirdre is a bloody-tragedy of double revenge based on the tragic love story of Deirdre and Naoise from the ancient Irish myth. Primarily, it is a classical work strictly observing the three unities. Nevertheless, it has been regarded as the most experimental modern play which is in the act of completing itself before the audience chiefly because of the musicians adopted for the various roles throughout its development. Originally, a most beautiful fourteen-year-old girl Deirdre raised in a secluded wood was found by the High King Conchubar of Ulster and became his betrothed, but she eloped with a young warrior king Naoise one month before her marriage. After seven years` wanderings, believing Conchubar`s promise to forgive him, Naoise returned home against Deirdre`s will only to be killed by Conchubar and Deirdre killed herself. But Yeats confined the story to the final phase after the protagonists` return and entirely modified or rewrote the better part of the story to create quite a new mythology in which both his private love for Maud Gonne and his patriotic love of his country are expressed. And in Deirdre we can witness the protagonists` pure passionate love is changed into a tragic joy through their ritual murder/suicide.