Historias de Letterexhange

What if you had a chance encounter with a stranger, in a fleeting moment, the encounter is over. However, the moment is etched into you, and you want to know more. One problem is that you don't know who they are or how to contact them again. What do you do? You write a letter and leave it hiding where you had that fated encounter (in plain sight, almost), hoping they will find it.