In 1972 a young girl posts a letter into the mailbox. A few days later , when the postman delivers it, the letter falls in between the mailboxes and the wall and gets stucked there.

In 2005. The lost letter is found behind the mailboxes when these are removed by workers refurbishing the wall. Mercedes, the letter's addressee, opens the envelope and finds out that it's an anonymous letter with some information that will change her life retrospectively.