 "In Search of the Castaways" was Hayley Mills' third film in the series of six for the Disney Studios.In England in the 19th century, Professor Paganel (Maurice Chevalier), a whimsical French geography professor, finds a bottle containing a note which he believes to have been written by the missing Captain John Grant (Jack Gwillim).Paganel and Grant's two teenaged children, Mary (Hayley Mills) and Robert (Keith Hamshere), approach John Glenarvan (Michael Anderson, Jr.) and his father, the wealthy shipping magnate Lord Glenarvan (Wilfrid Hyde-White), the owner of Captain Grant's ship, and persuade them to finance a search expedition.