Seeming tense and erratic, Captain Kirk takes the U.S.S. Enterprise into Romulan space and the ship is immediately surrounded by Romulan warships. Kirk and Spock beam aboard the Romulan flag-ship and confront the Romulan Commander. Kirk explains that his ship entered Romulan territory because of equipment malfunction. Spock denounces this explanation, saying Kirk ordered them here due to his reduced mental stability. Kirk attacks Spock, who returns the attack using the Vulcan death grip, killing Kirk. Kirk's body is returned to the Enterprise while Spock remains on the Romulan ship. Unknown to the Romulan Commander, this has all been a ploy to sneak the officers on board and steal the Romulan cloaking device. Disguised as a Romulan, Kirk returns to the Romulan ship and steals the vessel's cloaking device and returns with it to the Enterprise.

James Doohan (Lt. Cmdr. Montgomery Scott)
Joanne Linville (Romulan Commander)
Jack Donner (Romulan Subcommander Tal)
Nichelle Nichols (Lt. Uhura)
George Takei (Lt. Hikaru Sulu)
Walter Koenig (Ensign Pavel Chekov)
Majel Barrett (Nurse Christine Chapel)
Richard Compton (Romulan Technical Officer)
Robert Gentile (Romulan Technician)
Mike Howden (Romulan Guard)
Gordon Coffey (Romulan Soldier)

• The Romulan ships are the same design as the Klingon ships, due to "sharing of technology" (i.e., sharing of models to cut costs).