The novelist and screenwriter, Guillermo Arriaga, renowned for his work on the scripts for Amores perros, 21 Grams and Babel, presents his latest novel, El salvaje, which tells the parallel stories of Juan Guillermo, a teenage orphan with a desire for revenge, and Amaruq, a man obsessed with the persecution of a wolf in the icy lands of the Yukon. In conversation with Laura Revuelta.