Discovering a method of making himself invisible, scientist Daniel Westin destroys his notes and flees to avoid letting the secret fall into the hands of those who would use it as a military weapon. He finds refuge at the Klae Corporation think tank, where he and his wife resume efforts to find a way to make himself visible again.

The Klae Corporation requests Dan's help in determining whether a wealthy recluse is still alive and planning to make a corporate deal with a foreign government.

When priceless paintings are stolen from the Capitol building in Washington, D.C., Dan and Kate are asked to infiltrate a foreign embassy to find the perpetrators.

Dan and Kate attempt to expose a phony spiritualist who has been exerting undue influence over a powerful senator.

The Westins must prevent a suspected spy from being assassinated before they find out how she has been stealing documents, and to whom she has been selling them.

At a scientific conference in Stockholm, Dan must determine whether a former defector is sincere in his request for help to escape back to the U.S.

The Westins are asked by an elderly female janitor, also employed by the KLAE Corporation, to help her son who is in jail. While helping Dan inadvertently fouls up an undercover drug investigation.

When the Westins are caught in a bogus traffic violation while driving through a small town, Dan decides to take on the corrupt local officials.

The Westins conspire to help Walter's Aunt Margaret replace the money she "borrowed", from the bank where she is employed, to support her gambling habit.

When one of the corpration's co-owners, Caroline Klae, is threatened and then kidnapped after she refuses protection, one of the other siblings makes a grab for power.

Dan must rescue the blind daughter of a an organized crime kingpin, who has been kidnapped to prevent him from testifying against his cronies in court.

An escaped mental patient holds Director Carlson hostage and demands that he be given the secret of Dan Westin's invisibility.

Westin and DiMaggio attempt to help an Eastern Bloc figure, in danger from his own entourage, who wants a face lift to maintain his political popularity.