Don Matteo and his parishioners go on a pilgrimage to a sanctuary. They must hire buses for their trip. Two busses are from the Benassi bus company and one from the Passeri bus company.
There is bad blood, however, between the former partners, Benassi and Passeri. |  | During the trip, the Benassi bus driven by Mancini has an accident.
Blood tests reveal that the bus driver had a high alcohol content. Initial inquiries determine that the driver is responsible for the accident because the bus had recently passed its yearly inspection and in the past the man had been an alcoholic. | |
