Eleen
Julie Newmar

Kras
Tige Andrews

Maab
Keel-Cal Boder

Akaar
Ben Cage

Crewman Grant
Robert Bralver

Carrying out orders to agree a mining treaty with the inhabitants of Capella IV, Kirk, McCoy and Spock beam down to the planet's surface only to discover that they have been beaten to their goal by a Klingon. A security man tries to shoot the aggressive Klingon but is killed by the Capellans who then confiscate their weapons to keep the peace.

The landing party is taken to the Capellan leader, Teer Akaar, who Kirk tries to persuade to sign up with the Federation. During that night a revolt occurs and Akaar is killed. The new leader, Maab, takes the Starfleet officers prisoner but they manage to escape, along with Akaar's heavily pregnant widow, Eleen, who Maab has threatened to kill.

During the excitement, the Enterprise has been forced to leave orbit to answer a mysterious distress signal. Faced with no other choice, Kirk, Spock, McCoy and Eleen make their way into the mountains where, using frequencies from the communicators they managed to retrieve during their escape, they cause a landslide to slow down their pursuers. Eventually, Eleen can travel no more so Kirk finds a defensible cave where they can hole up. While McCoy prepares for the baby's birth, Kirk and Spock set about making some primitive weapons to defend themselves if necessary.

Aboard the Enterprise Scotty realises that the distress call was a fake intended to lure them away and makes full speed back towards Capella IV. Eleen gives birth and has already decided that the fatherless baby will belong to McCoy. She knocks McCoy out and escapes, making her way back to Maab and tells him that the Starfleet officers and the baby are all dead. The Klingon disbelieves her and starts climbing the rocks, heading towards the cave where he is shot with an arrow fired by Kirk.

Eleen persuades Maab against the Klingon as he had the temerity to call her, a 'royal personage', a liar. Maab heads towards the injured Klingon, who understands what is happening and shoots him. Seconds later he, himself is killed by the Capellans. The new baby boy is named James Leonard Akaar after McCoy and Kirk and they are now in a position to be able to sign a Federation agreement with the new Teer's regent, Eleen.