Ava, 13, knows that she will soon be blind, a sad reality that her mother prefers to ignore. Her mother wants Ava to forget about what's happening and focus on enjoying their vacations by the sea. But Ava doesn't see it that way. She tries to practice walking blindfolded, with the help of the big black dog she steals from Juan, a young man on the run.
One evening while walking on the beach in the company of the dog, whom she has named Loupo, the teenager decides to go for a swim. Juan quietly watches and then when he has a chance, comes out of his hiding place and discreetly leaves with his dog. A few days later, Loupo returns to Ava, his fur covered in blood.