Two sailors discover a way to beat the roulette tables in a Venice casino.

After tracking missiles with an electronic brain (Operation Honeymoon), a U. S. battleship lays anchor off Venice. Almost immediately, young and brash Lieut. Fergie Howard hits upon the scheme of using the electronic computer to break the roulette table at the Lido casino. Aided by the reluctant Ensign Gilliam and civilian missile expert Jason Eldridge, Fergie blinker-signals all the data on the pattern of the casino game table to the ship, has the data fed into the machine, and receives back the likely winning numbers. Complications arise when Fergie falls for young Julie Fitch, who just happens to be an admiral's daughter; and Jason becomes involved with a former girl friend, a nearsighted millionairess named Pam Dunstan. The girls decide to cooperate, however, and once the plan is put into operation the boys amass a fortune. But further problems develop when the blinker communications are intercepted by Admiral Fitch and some Russians, both of whom mistakenly assume that they relate to aggressive military measures. An alcoholic signalman, Burford Taylor, stumbles upon the foursome, learns of their activities, and reveals all to the admiral. But, after a riot at the casino, Fergie talks his way out of a court-martial and even gets the admiral to accept him, albeit reluctantly, as a son-in-law. And young Jason decides that being married to a millionairess might not be so painful as he previously imagined.