The Enterprise deliberately crosses the Neutral Zone, on Kirk's orders, into Romulan space and is promptly surrounded by Romulan warships, each equipped with a “cloaking device“ that renders it undetectable. Spock betrays the apparently irrational and paranoid Kirk to the Romulan commander, a woman who is obviously attracted to Spock. A deadly game between Kirk, Spock and the Romulans risks not only the Enterprise but the tenuous cease-fire between the Romulans and the Federation.