Five Union soldiers in the American Civil War escape in a balloon. Driven by tremendous find themselves castaways on a strange island somewhere deep in the Pacific Ocean.
They call it Lincoln Island -- and through luck, pluck and the help from a mysterious hidden benefactor, they not only survive but become more like colonists than castaways. With their leader -- an engineer named Cyrus Smith -- they recreate the wonders of nineteenth century civilization with what they find on the island. Along the way, the "colonists" rescue Ayrton (a character from another Jules Verne novel, "In Search of the Castaways") who has been living like a wild creature. In this book, the third part of "The Mysterious Island," they must deal with Ayrton's former shipmates -- bloodthirsty pirates . . . and discover "The Secret of the Island." Namely, their mysterious benefactor, who turns out to be none other than one of the most famous characters of science fiction -- with his wonderful invention!