While Tom Swift is working on his latest new invention, the electric rifle, he meets an African safari master whose stories of elephant hunting sends the group off to deepest, darkest Africa. Hunting for ivory is the least of their worries, as they find out some old friends are being held hostage by the fearsome tribes of the red pygmies.
Swift builds two major inventions in this volume. The first is a replacement airship, known as The Black Hawk. This new airship is to replace The Red Cloud, which was destroyed during his adventures in Tom Swift in the Caves of Ice. This airship is of the same general construction as The Red Cloud, but is smaller and more maneuverable.