[2] The European characters arrive to study the feasibility of flooding a low-lying region of the Sahara desert to create an inland sea and open up the interior of Northern Africa to trade.

In the end, however, the protagonists' pride in humanity's potential to control and reshape the world is humbled by a cataclysmic earthquake which results in the natural formation of just such a sea.

[4] The French military escort, led by Captain Hardigan, meet with conflict from Tuareg Berber tribes who fear the new sea will threaten their nomadic way of life.

The Berber tribes, led by the warlord Hadjar, begin an insurgency campaign against the Europeans in an effort to derail their plans for the inland sea.

[6] Others had made similar proposals at the same time,[6] and canal building generally was a popular geopolitical endeavor of the first decade of the 1900s, when Invasion of the Sea was written.

For years before the Baxter translation, Invasion of the Sea was one of four late Voyages Extraordinaires novels left unpublished in their whole form (the others being The Mighty Orinoco, The Kip Brothers, and Traveling Scholarships).

Publishers Weekly criticized the character development (with the exception of that of an affable dog named Ace-of-Hearts), while also describing the plot as both "disjointed" and "predictable", saying that the book is overwhelmed with a "deluge of scientific facts".