Famous five  befriend an orphaned circus boy,,Nobby, who is in a procession of horse-drawn circus caravans. This inspires George to suggest a caravanning holiday. Julian's parents assent and hire two caravans for the children. They travel to Merran Lake, where they are reacquainted with Nobby and meet various animals. The Five camp on a hillside, much to the annoyance of Nobby's guardian, Tiger Dan, and an acrobat named Lou, who want them to leave. One of the caravans of the children is directly above the entrance to a network of caves, where Tiger Dan and Lou have hidden stolen valuables. Assisted by Nobby, Timmy and a chimpanzee named Pongo, the four children manage to outwit the crooks. After the criminals are arrested, Nobby leaves the circus to live with a local farming couple and look after their horses.