Deanna Troi is unknowingly brought aboard the Romulan Warbird Khazara and has cosmetic surgery to make her look like a Romulan. Subcommander N'Vek privately explains that he has no intention of harming her, but needs her help to pose as Major Rakal of the Tal Shiar, the Romulan intelligence service and secret police. N'Vek is currently engaged in a plan to deliver secret cargo to the Federation, and needs Troi to act her role to convince the Khazara commander, Toreth, who is not aware of N'Vek's plan, into complying with his directives. Troi, as Rakal, is able to sway Toreth to head for a planned rendezvous in the Kaleb sector under threat of intense interrogation techniques.
Aboard the Enterprise, the crew brings aboard Stefan DeSeve, a human who had served as an ensign in Starfleet before defecting to the Romulans. Now he has returned with a message from Ambassador Spock. Captain Picard, wary of DeSeve's motives and ready to arrest him for treason, considers Spock's message regarding a meeting in the Kaleb sector that would be prudent for the Federation's interest, and directs the ship there.
As the Khazara is en route, N'Vek shows Troi the secret cargo - Vice Proconsul M'ret and two of his aides, held in stasis. M'ret has desired to defect to the Federation, and his presence there would aid further Romulan dissidents to flee the Empire. The plan is to transport the stasis chambers to a Corvallen cargo ship at the rendezvous point, who will subsequently deliver them into Federation space. When the Khazara meets up with the cargo ship, Troi senses its captain is not trustworthy, and N'Vek fires upon it, destroying it. He claims he was ordered by Major Rakal. Toreth is furious. She later explains to Toreth that she recognized the captain of the cargo ship as a known Federation spy.
The Enterprise arrives at the Kaleb sector at the designated time and coordinates but find no trace of the cargo ship. They start a search of the section, soon finding the wreckage of the vessel. As the Enterprise moves in, Toreth takes this as a sign of N'Vek's truthfulness. N'Vek, in private, explains to Troi that their only other option is to travel to Draken Four, an entry point for the Federation, where Troi can use her Starfleet codes to allow the ship to enter undetected. Troi gives this order to Toreth, but the captain points out that with the wreckage nearby, they will be detected, and has the ship travel some distance away while the Enterprise continues to search. Troi is worried that the Enterprise will not be able to follow them, and has N'Vek create a small imbalance in the engine. The Enterprise crew detect the imbalance and follow the trail of the cloaked ship.
Toreth learns of the Enterprise trailing them, and asserts that there is a traitor on board, and directs the ship to ram the vessel. Troi steps in as Rakal and takes command from Toreth, then orders the ship to decloak and hails the Enterprise, offering to discuss the matter. The Enterprise crew, though they recognize Troi, feign ignorance and take down their shields. N'Vek fires on the Enterprise with low-powered weapons, appearing to damage the vessel but in reality, a means to mask the transport of the stasis chambers to the Enterprise. Toreth realizes that she is being deceived, and has N'Vek killed, and is about to kill Troi when she is safely transported to the Enterprise. The Khazara cloaks and returns to Romulan space, while Troi's cosmetic surgery is reversed, and she contemplates the value of N'Vek's efforts to aid the Federation.