The Castaways are dealt a heavy blow when they discover through the "Esmeralda Log" that the island they are on is well away from shipping routes.

The Castaway family suffers thirst when the island is hit by a drought, causing the two youngest children to fall ill.

David and Angy set out to join the men, and when they meet Irving he takes them through a new route. They become lost

David befriends a native boy who is being hunted by killers from another tribe.

The castaways prepare a beacon to attract ships, and when they find it ablaze one night, they think islanders must have lit it. The women are alarmed and wish to leave the island, but the men vote to remain.

One of the prisoners makes a deal with the other castaways to take possession of an islander's canoe. The castaways begin building a boat to take them to Australia, but Irving, who faces imprisonment there, has other plans.

An ongoing feud with Sergeant Holt motivates the two convicts among the castaways to establish their own camp.

The castaways react with alarm when Cathy comes upon a wounded savage in the jungle.

The two youngsters in the party of Castaways, David and Angy, go off in search of food along the shore. They become alarmed when they see a canoe of painted cannibals, out hunting . . .

A cyclone hits the castaways' camp, bringing gold from the wreck of the Mary Jane---and destruction. A storm destroys in one stroke everything that the castaways had painstakingly built up in five weeks. Jan Lindberg is proposing to build a weatherproof hut. However, Billy, Irving and Holt are with their thoughts somewhere else: they have found a few pieces of gold: the remains of the ship's treasury.

The harmony among the castaways is disturbed when another shipwreck survivor Irving---a convicted criminal---makes it to the island.

Irving (Don Barkham) is the convict whose obsession with the idea of escaping to the Dutch East Indies disrupts life among the survivors.

The survivors build a stockade and explore the island. The island, their first place of rescue, appears to the survivors of the Mary Jane as a prison. The castaways will soon realize that this is one of the many South Sea Islands located far away from the Australian mainland.

On her way from England to Australia the ship "Mary Jane" gets lost in a storm and capsizes in the vicinity of an uncharted island in the Pacific. The family Lindberg, Sergeant Holt, Harper a convict, the boy David and Billy, who works as a seaman and a young Englishwoman, Cathy, are the only survivors hoping to be rescued from this uncharted island.