While the estate matter is being settled, Alex leaves for Capri to unsuccessfully pursue an affair and Katherine remains in Naples visiting museums and archeological digs and thinking about that sickly young poet who stood outside her window in the rain.
Just like in Stromboli, the rugged, imposing background- active Mt. Vesuvius, which erupted only a few years before, reveals the chasm between the couple.
There are a lot of driving shots. Rossellini emphasizes the couple's isolation and strict observers status as life happens outside the windshield of their car - Naples with its crowded streets, religious processions, livestock, a river of humanity on the other side of glass.
While narratively weak and with the unconvincing ending, Viaggio in Italia is, as Deleuze points out in Cinema II, the prototype for what's to come - Antonioni's Urban ennui and isolation in L'Avventura and La Notte.