Really three major adventures, one leading to the next.
In the first, Dr. Lowe goes up against Hells Angels bikers from Canada using invisibility technology to smuggle pure heroin into the States from Afghanistan.
In the second, Lowe allows himself to be 'recruited' by the North Koreans to perfect their invisibility techniques, all to learn how far along they are and to steal from them.
In the third, Lowe goes up against North Koreans trying to smuggle and explode a stolen USSR nuclear bomb into an American city.