Role in the film
Father Murphy enters the Rathcullen Arms as he listens to one of Darby O'Gill's stories about his encounter with King Brian, the king of the leprechauns. After finishing his story and telling a joke about leaving Paddy Scanlon's share of the gold to the Church without letting Father Murphy know where he got it, everyone laughs at this joke including Father Murphy until everyone notices him in the pub and stop. Not offended and quite the understanding man with a little sense of humor himself, Father Murphy simply proceeds to announce the good news to everyone about their new bell finally arriving to them.
When asking if someone could help him retrieve the bell for him from Glencove, Pony Sugrue asks how much would someone be paid for it. Father Murphy generously offers 2 pounds to whomever does it but Pony agrees to do it as long as he is paid 2 pounds, 10 rather than just 2 pounds; a deed which Father Murphy states might even "absolve a man from the sin of using the priest and the Church against the powers of darkness for his own selfish ends." So, Darby kindly agrees to do it for nothing. But Father Murphy generously and kindly intends to reward him with the music of the bell in return for his good deed and for "his seed, breed, and generation till the end of time." So, Darby agrees to do it in the morning. Then, Darby's daughter, Katie comes in while speaking but a few words to Father Murphy and drags her father out of the pub to catch up before Lord Fitzpatrick finds him in the field.
In the morning, Father Murphy and everyone else comes out to find Darby having successfully returned with the new bell from Glencove. Father Murphy thanks him and then he asks him what he has in the sack when he notices something (King Brian) moving in it. After playing a small battle of wits with each other, Darby simply states he doesn't have anything at all but Father Murphy still remains unconvinced and simply smiles either way.
The next night, after Katie has injured herself from falling off a cliff at the top of Knocknasheega and fallen ill, Father Murphy can be seen in her room with Molly Malloy, Michael MacBride, and Darby praying and probably mourning for her. When Darby notices the Banshee and the cóiste-bodhar (Death Coach) coming for Katie, he elects to use his final wish to go in his daughter's place. King Brian is deeply saddened at Darby's wish, but grants it, but once Darby is on his way to the next world, King Brian reappears in the Death Coach and tricks Darby into making a final fourth wish ("wishing" that his friend could join him in the afterlife). Because he is only allowed three wishes, this negates all the previous wishes and spares Darby's life. Darby is saved and King Brian has (literally) the last laugh in their running battle of wits. Because of his deed, Katie's fever has broken and she and Michael reveal their love for each other. Believing Katie's recovery to be a miracle, Father Murphy is pleased and leaves to return to the church after that.