A young immigrant finds himself lost in Mexico City where he meets a charismatic street vendor who introduces him to selling pirate music in the city underground

This logline reveals an interesting set up for a story, but as has been noted previously, lacks stakes and an antagonist. What probably will clarify things for you is if you work the protagonist's goal into the logline - "After a street vendor inducts him into the world of music piracy, a timid immigrant must (goal), before (antagonist & stakes)."

I'd like to know something more about the protagonist. Rather than just being young, is he naive? a farm boy? Anything that makes the selling of pirated music more interesting, more ironic.

Thanks Kriss and Chasfisher for your feedback.I agree with you both. Now that I read the logline it's lacking the second part of the story. The whole story will actually take place in the underground and it's only at the end that the main character needs to decide whether or not to continue in this "new world" after enduring many things. I'm trying to rewrite it but find it difficult to summarize so many things in one line! thank you. :)