The story follows the journey of three monks of the Cantorian Order of monks, who have until recently lived in the ancient Auersberg Abbey in Brandenburg. The Cantorians speak Latin, and maintain a religious life, in which hierarchy plays a minor role. They believe that the Holy Spirit is revealed in music, particularly in the vocals. Because of this heretical doctrine, the Cantorians have been persecuted by the Roman Catholic Church since 1693. Only two monasteries survived, one in Brandenburg and the mother house at Montecerboli in Italy. At the time of the film's events, the two monasteries have not been on speaking terms for two hundred years, because Auersberg kept the unique manuscript copy of the order's rule, Regula cantorianorum, against the wishes of Montecerboli. The German community in Brandenburg is facing ruin, the monastery is dilapidated and run down, and the order can't pay the mortgage. On the death of the last Abbot, Stephen, who had always shielded his monastery from the world, the remaining three monks, following Abbot Stephen’s dying behest, abandon their home to join the mother house in Italy, taking the Regula with them. Totally unprepared for the outside world, the three monks start off on foot across Europe, until they cause the young journalist, Chiara, to veer off the road in her classic Mercedes-Benz convertible. She subsequently helps them to reach their destination. Along the way, each of the monks faces his own temptation. Brother Arbo, the youngest monk, who has lived in the monastery all his life, falls in love with Chiara, and Brother Tassilo is drawn to return to his parents' farm, which his widowed mother is now running alone. Bibliophile Brother Benno, meanwhile, is tempted away from his vows by the Jesuit library in Karlsruhe and its malevolent head, Pater Claudius Leis, formerly Benno's rival in love.
As the Gloria song at the Jesuits' conventual Sunday Mass, they sing a three-part setting of Georg Neumark's 17th century hymn Wer nur den lieben Gott läßt walten, written for the film by Tobias Gravenhorst, who also plays the organist.
At the end of the film in Montecerboli, the reunited order sings again Tu solus.
Music plays an important part of the story-line, with the three monks spontaneously breaking into song throughout the film, although it would be wrong to consider the film a musical, as the music does not advance the plot as in a musical: the story is about a group of monks who sing. Similarly, although it has elements of both comedy and romance it would be wrong to call the film a romcom.
