Avellaneda's Moon is a social club in a middle-class neighborhood. During a crowded dance, a woman goes into labor. She gives birth right there, and Román is born. As a result, Román Maldonado (Ricardo Darín) will have a lifetime free membership to the club.
Thirty-something years later, the club is on the verge of closing due to massive debts. Román will have to make the final decision, and a sign of his indifference is that he has lost the membership card, and doesn't bother to look for it. Despite having limited financial resources, the final function continues, albeit with difficulties.
One of Román's sons, who has just been fired in a bad way from a lousy job, has managed to gather enough money to travel to Spain and look for work there. Although Román initially disapproves, he eventually approves the decision and even wants to go with him.
There are constant references to the country's economic situation and the change in the purchasing power of the neighborhood residents, who are now lower class instead of middle class. There are also problems with the club's management: many members do not pay, and money is spent without control, etc.
Román's brother - who does have money and engages in shady dealings with politicians and businessmen - plans to demolish the club to make a big real estate deal. The situation is hopeless: the club must close due to its multiple debts.
Just as Román is about to make the trip to Spain, he finds the famous lifetime membership card in a garage where he keeps all kinds of junk. He looks at it nostalgically, and at that moment decides to stay in Argentina and open a new club right across the street, La Luna de Avellaneda, which will be more modern and better organized.