The Golden Head (1964)

Milly, Michael and Harold Stevenson are in Budapest with their father, a British inspector who is attending an international convention of criminal investigators. Two thieves use the conference as an opportunity to steal the golden bust of Saint László from the Cathedral of Gyór and attempt to smuggle it out of the country. The Stevenson children trail the thieves through Budapest and the surrounding area, providing a widescreen travelogue of the culture and landmarks of Hungary.