2 years after the events of the previous film, Jack Griffin is still invisible and is still becoming a deranged maniac more and more. He is soon killed by the authorities and his assistant soon takes the potion to become invisible because he thinks he found a way for the user to not go mad. However, due to a much more potent formula, he actually becomes madder and more deranged, quicker and even more so. He once again goes on a killing spree just like the previous Invisible Man. His close friend tries to make a formula to cure him, but it might be too late.