In the book, the protagonist Carlos uses his art -- playwriting -- to fight against the oppression of the corrupt government that is abducting defiant citizens. He is not altogether successful in that his actions lead to several deaths as well as his own losses, but he is able to continue the spark of rebellion in the hearts of the citizenry, who otherwise may have allowed themselves to be beaten down by the constant murder and torture of their friends and family. Carlos uses art as an expression of his own feelings and as a reflection of his circumstances.
...Carlos Rueda is first and foremost a storyteller, whose gift allowed him to make many children in Beunos Aires happy, and only when the generals began their indiscriminate killing did he discover another dimension to his art, which will forever remain a mystery.
(Thornton, Imagining Argentina, Google Books)
The art itself is not what saves Argentina; Carlos does not singlehandedly topple the corrupt regime. However, what art accomplishes in the story is, in some ways, more important; it kindles and reignites the feelings of oppression and righteous anger felt by Carlos and others, and is a tool of rebellion that spreads without direct action. In the end, Argentina is saved not by art alone, but by art as a tool for freedom and liberty; through his art, Carlos allows others to feel solidarity and indignation, and ultimately distributes the courage to stand up and act where otherwise they may have fallen silent.