During a bus ride through the Andes, two seminarians encounter with a woman named Manon. Immediately, one of them falls in love and the attraction is mutual, so they decide to flee to capital city to start a new life. But the love of Manon ambitious drags this man to leave his vocation and commit criminal acts to maintain a life of luxury and extravagance.
Commissioner Leon (Miguel Angel Landa) investigates the murder of a woman in a population near the capital. The woman was raped before death and the case is complicated when his brother becomes the prime suspect, since it is a priest (Eduardo Serrano). Because of the implications that inquiries might have, Leon is pressured to keep the event as a "crab" (Cangrejo, or a unsolvable case), but he decides to comply with the law.
