Documentary that explores the unknown and mysterious world of whales that appear for a few weeks a year on the Catalan coast. Mar dreams of being able to record the sound of whales, which appear in the Mediterranean only a few weeks a year, depending on circumstances such as the amount of rain and krill, the food on which the whales feed. But when he embarks with a team that investigates cetaceans, Mar realizes that in order to listen to the largest animal in the world we must be silent.