Strange things are happening in the carriers' guild: a madman has sown death and paranoia among the truck drivers, and Mario hasn't been himself lately: he's excessively serious and he no longer has a sense of humor. In the midst of the collective hysteria, Fernando begins to doubt his brother Mario, and the fear and the murders continue until there is an attempted rape. Mario also has his doubts about Fernando, and a detective embarks on the investigation with a team of agents disguised as truck drivers to find the real culprit, with results that range from the obvious to the unintentionally humorous.