Alejandro falls in love with Mariana, but he doesn't know how to approach her, so he starts sending her love letters. Mariana immediately falls for a mysterious author of romantic letters. The only person who knows the real author of those letters is Oscar, Alejandro's best friend, who takes advantage of the situation and wins Mariana over behind Alejandro's back, telling her that he was the one who sent the letters. Mariana is confused, since something about Oscar's personality tells her he couldn't have written those letters. And Alejandro still doesn't have the courage to confess the truth.