While searching for two missing physicists who've made a breakthrough in cold fusion, a secret agent encounters an equally secret and capable blonde who is in competition with him.

Now forced to work together and masquerading as a suburban couple, ""Mr. and Mrs. Smith"" spy on their neighbor who is suspected of stealing top-secret information from his employer.

With the assistance of a nerdy bookkeeper, Mr. and Mrs. Smith go to sea to spy on a shipper who is suspected of stealing 200 Stinger missiles.