The play is set in County Mayo in a country shebeen or pub. Pegeen Mike is engaged to Shawn Keogh a rich farmer, but she is not in love with him. Pegeen’s father Michael James owns the pub, and spends his time going to wakes and getting drunk. A young man arrives one evening as Michael James and his two pals Jimmy Farrell and Philly Cullen are about to go off to a wake. This young man calls himself Christy Mahon and claims that he has killed his da. Everyone including Pegeen are fascinated and admire Christy for this heroic deed.
The men set off for the wake leaving Pegeen with Christy. The widow Quinn a local woman who is supposed to have murdered her husband arrives and tries to get Christy to stay the night in her hut. Pegeen has taken control of Christy at this stage and refuses to let him go. The following morning some local girls arrive to visit Christy and bring him presents. Christy is a hero in the eyes of the villagers and they beg him to participate in their local games. In the meantime Old Mahon who is Christy’s father arrives and meets the widow Quinn. Old Mahon has suffered a blow on his head from being hit by Christy and wishes to punish him. He tells the widow about Christy and describes him as a weak character, ‘a dirty stuttering lout who would get drunk on the smell of a pint. ‘
When Christy meets his father towards the conclusion of the play he gives him another blow on the head and it truly looks as if he is dead. The villagers including Pegeen decide to capture him and bring him to prison. Pegeen disowns him for being a liar. Old Mahon recovers however and he and Christy leave the shebeen mocking the villagers who are unable to accept reality when it lands on their own door. The play concludes with Pegeen lamenting the loss of the ‘only playboy of the western world.’ She is left with her loveless alliance to Shawn Keogh.