A British intelligence agent, Major McGuire (Dirk Bogarde), is on the trail of Haghios (George Chakiris), the leader of a group of terrorists engaged in the fierce and bloody struggle for Cypriot independence. Juno Kozani (Susan Strasberg), an American student visiting friends, unwittingly discovers they are hiding Haghios. McGuire is convinced that Juno knows Haghios' whereabouts, but she refuses to confirm his suspicions. Meanwhile, Haghios is convinced that Juno has double crossed him and attempts to silence her. Fearing for her life, McGuire hides Juno in his apartment for protection, and his efforts become further complicated when the two fall in love. After a shoot-out at his flat, McGuire is transferred by British intelligence to Greece, Juno follows him there, as does a mysterious agent who has plans for them both.