In the early 20th century, José Diogo, a man born and raised in Porto Alegre, decides to visit some relatives who live in an isolated rural area in the interior of Rio Grande do Sul. Upon arriving there, amid festivities fueled by barbecue, chimarrão, and wine, he is enchanted by the beauty of young Sofia, but also discovers that these people live in fear of the stories of a werewolf that inhabits the region. Incredulous, he decides to investigate and ends up uncovering a terrible secret that will bathe the nights of the full moon in blood. A typically Brazilian werewolf story, based on Gaucho folklore, but told in a different way.