A group of young pixies gathered under a large oak tree listen to a story told by an old Irish leprechaun known as The Ancient. The story, about humans, begins in the garden in 1870: Under the oak tree, a young Irish musician known as The O'Monahan plays a song of love to his American sweetheart, Rena Fairchild, who lives on the other side of the garden wall. Hearing the song, Rena enters the garden and kisses The O'Monahan. Rena is followed to the oak tree by her three American suitors, Richard Gaunght, a young medical student; James Trumbell, a lawyer; and Theodore Findley, a banker. Rena rejects all three of her suitors, and instead decides to live with The O'Monahan in Ireland. Before leaving for Ireland, The O'Monahan blesses the three men and wishes them all the success they desire. Forty years pass, and the three suitors, now at the pinnacle of their careers, are friendless and live together in a large house. One day, the three old bachelors donate part of the property that Rena gave to them years earlier to the local university as a site for a future amphitheater. Soon after, they are surprised by the arrival of Sheila O'Monahan, the young granddaughter of The O'Monahan and Rena. Sheila, accompanied from Ireland by the O'Monahans' servant, Terence Aloysius O'Davern, explains that her parents are dead and that she is to become the ward of the three men. When the men reject Sheila, she and O'Davern are left with no alternative but to live in Rena's old, dilapidated house. Meanwhile, complications arise in the proposed amphitheater construction when it is discovered that the deed that Rena gave the three men is to her swamp property, not the property on which the old house stands. The three men realize that their only hope in getting the deed to the main estate is through Sheila. While tearfully considering her desperate situation, Sheila, meanwhile, suddenly remembers a story her grandmother told her about the old oak tree on the property. Sheila goes to the tree and requests the help of the fairies, and at that moment, the three bachelors arrive and invite her to live with them. Believing the invitation to be an act guided by the fairies, Sheila gladly becomes their ward. However, when Sheila learns that the men intend to tear down the old house and destroy the old oak tree, she decides to take back the deed. The three men attempt to change her mind by promising to move the oak tree to a different location, but she refuses, insisting that the leprechauns would be killed if the tree were moved. Determined to get the deed, the three men hire circus midgets to pose as leprechauns and pretend to abandon the tree. Sheila falls for the trick, and later gives the deed to the three men. When O'Davern exposes the ruse, however, the judge who gave the men custody of Sheila removes her from their home and places her in an orphanage. One day, Sheila escapes from the orphanage, enters a convent and tells her story to Sister Mary Brigid. Sister Mary then visits the three bachelors, upbraids them for mistreating Sheila and demands that they save the old oak tree. As demolition crews begin tearing down the old house, Gaunght chains himself to the tree and refuses to move. Trumbell eventually joins Gaunght in his protest, and the tree is finally saved when Findley spends all his money to prevent the tree from being torn down. The good deeds of the three old men restore Sheila's faith in mankind, and all are happily reunited.
