Carla Perez, a young Cuban postal clerk, discovers that, by changing a word here or there in the letters that pass through her hands, she can bring joy and happiness and eradicate the blues. She begins to modify letters, adding her own words and feelings. At the beginning, it’s just a game to help her escape the dullness of her existence. But soon she finds herself caught up in changing the reality of her fellow citizens as they search for happiness. She falls in love with a postman. But when she becomes one of the lucky winners in the annual lottery of American visas, a new horizon opens (flee the routine, get out, emigrate to the United States) and Carla realizes the choice of staying or leaving is not easy to make.