The book follows the adventures of the Seagrave family who are shipwrecked at sea, and survive on a desert island with the assistance of veteran sailor Masterman Ready.

The Seagrave family are returning to New South Wales on board the Pacific when a storm strikes, wrecking the ship.

[2] The Seagrave family, together with their young black female servant Juno, and the veteran sailor Masterman Ready, are shipwrecked on a desert island.

[2] The family learn to survive many obstacles, helped by Ready's long experience of life as a seaman.

[4] The Seagrave family in Marryat's novel have to overcome many hazards, beginning with the initial storm which wrecks the ship and injures the passengers.