Riccardo, a sessions musician, has a job in Munich - but he's promised to spend Christmas with his little son Junior in Italy. An invitation to perform in a live broadcast in Munich on Christmas Eve interferes with his plan. He nevertheless decides to secretly go and fetch his son from Northern Italy and take him back to Munich with him, while the singer Michelle - a recently rekindled "old flame" from Riccardo's teenage days - covers for his absence. Meanwhile, however, Junior himself is setting off for Munich, accompanied by his grandfather, the former violin virtuoso Vittorio Orlandi. When grandfather and grandson encounter passport problems and are forced to escape from the border police they meet up with a couple of crooks who give them a lift for part of the way. There's a mix-up of violin cases at this point, however: Vittorio is now unwittingly transporting the crooks' stolen jewellery rather than his precious violin. Naturally, the villains are soon back on the pair's trail, ...