Hello! Act 1 is set in a two bedroom tenancy in a tenement house in Dublin. The apartment is occupied by the Boyle family, which consists of Captain Boyle, Juno Boyle (his wife), Mary (their daughter), and Johnny (their son). When the play starts, Juno and Mary are discussing the murder of Mrs. Tancred's son. Juno doesn't think very much of her husband. She insinuates that he doesn't make enough money, that their health insurance has run out, and that his unemployment benefits won't last long either. She complains that he's always singing and that her husband is wearing out her nerves with his lackadaisical attitude.
Jerry Devine enters in Scene 2, asking about the Captain. He wants Juno's husband to know that Father Farrell's cousin is the foreman at a job in Rathmines, and that this cousin of Father Farrell would be willing to hire Captain Boyle if he would make his way up there. Jerry later delivers the news to Captain Boyle himself, but the Captain complains about the pains in his legs, and that he could never endure such a job.
We eventually find out why Jerry is so eager to be helpful to the Boyle family. He is sweet on Mary. However, Mary is in no hurry to accept Jerry Devine's proposal. Jerry tells her that he will likely be elected Secretary of the Union, as he only has one challenger. He is also popular with the men, and thinks he can pull the election off. What's more, if elected, the job will pay three hundred and fifty pounds a year, and Jerry thinks this will be more than enough to provide nicely for them both after they are married. He tries in vain to remind Mary of the good times they have had together. Mary is not too impressed; she just wants Jerry to leave her alone. Jerry accuses her of having found someone else and that he actually saw her hanging on the arm of some man coming out of the Cornflower Dance Class. Jerry tries to hang on to Mary's arm in order to prevent her from leaving without giving him a favorable answer; he pitifully begs to be allowed to kiss her "little, tiny white hand," but is rebuffed again. So, the argument comes about between Jerry and Mary because Mary is not interested in Jerry's marriage proposal.
Thanks for the question.