In a remote and mysterious region of Africa, a team of scientists led by the brilliant yet eccentric Dr. Felix Benet embarks on an expedition that will change their lives forever. During their exploration, they discover a strange radioactive mineral that emits a mysterious energy. This mineral has the potential to cure diseases but also harbors a dark secret that will soon be unleashed.
Upon returning to civilization, Benet, played by Boris Karloff, becomes obsessed with the mineral and its properties. His scientific curiosity drives him to experiment with its power, but the outcome is disastrous. Gaining the ability to become invisible thanks to the radiation, he triggers a series of events that transform him from an innovator into a dangerous criminal. The line between science and madness blurs as he embarks on a path of destruction, using his newfound ability to wreak havoc on those who stand in his way.
As his friend and colleague, fellow scientist Dr. John Benson, tries to stop him, the tension escalates. The authorities' hunt for the invisible man, led by a daring detective, turns into a game of cat and mouse. As the story unfolds, themes of ambition, power, and the fragility of human morality in the pursuit of knowledge are explored, leaving the audience with a haunting reflection on the limits of science.