[1] The novel tells of a wealthy young man, Godfrey Morgan, who, with his deportment instructor, Professor T. Artelett, embark from San Francisco, California, on a round-the-world ocean voyage.

The island is uninhabited and there are only two bidders: William W. Kolderup, a very wealthy San Franciscan, and his arch-rival J. R. Taskinar, a resident of Stockton, California.

Acceding to his nephew's desire, Kolderup sends Godfrey on a sea voyage around the world, aboard one of his steamships, the Dream, commanded by Captain Turcott.

At the time of publication, it was common for a young man of wealth to undertake travel as an educational rite of passage; for example, the California heir Leland Stanford, Jr. took two European Grand Tours: one in 1880-81, and the second in 1884, during which he died.

[2] The novel was adapted (very loosely) as a 1981 USA/Spain co-production by director Juan Piquer Simón, titled Jules Verne's Mystery on Monster Island (Spanish: Misterio en Isla de los Monstruos), starring Peter Cushing and Terence Stamp, with David Hatton, Ian Sera, Paul Naschy, Blanca Estrada, Ana Obregón, and Frank Braña in supporting roles.

[3] Monsters were prominently included as an element in the film are also fake made by an famous toymakers, but were absent from the novel, in which the villain J. R. Taskinar introduces non-indigenous carnivores to the island to take revenge on Kolderup for his auction win.