Through a mysterious voice from the bottom of the sea, Drowning Letters tells the most tragic years of our contemporary history. Following written letters, from mothers to their children, the voice accompanies the Spanish NGO rescue vessel, Open Arms, in its most dramatic mission. Forgetting that it is a true story, the situation gets worse when the film takes us aboard a Libyan coastguard military vessel and show us the most dangerous place in the world, in Libya, where human beings are being mistreated and enslaved.