In the Cold War, when the captain of a Russian submarine comes too close to the Gloucester Island in Massachusetts to give a look at America, the submarine gets stranded. A nine-man team commanded by Lieutenant Rozanov goes onshore to search a motor boat to release the submarine and arrives at the summer house of the New Yorker writer Walt Whittaker that is spending the weekend with his family in Gloucester. When he realizes that they are Russians, he believes that it is an invasion. Soon the information leaks, leading hysteria and paranoia along the inhabitants of the small village.