Stephen Kandel wrote an unused script for a proposed Planet of the Apes TV series episode. The final draft of Hostage, dated April 5, 1974, followed on from the already-written TV series concept, and featured Virdon, Kovak (later renamed 'Burke') and Galen as fugitives from ape leaders Zaius and Ursus (later renamed 'Urko').
The fugitives approach a sleepy human village Galen used to visit as a schoolchild. New 'Human Control Laws' mean the humans can't leave their village without permission from the apes, but they see a woman called Katrin sneak out and into an area of undergrowth. Chimps Aro and Manus soon follow the same route and the trio fear she will be discovered and punished. When a gorilla soldier also appears, they follow the others into the undergrowth and discover a concealed trapdoor. Before they can open it themselves, they are grabbed by Grayson and another human and brought down into an underground shelter. There, they meet humans Katrin, Black & Decker and chimps Aro, Manus & Lora - who had taken Galen's ethics course at school, where Galen was in the Free Speech Movement - who are a chapter of the UFF (United Freedom Force), a human/ape equality movement banned by Ursus. Above ground a gorilla UFF leader, Kemmer, is hunted by gorilla soldiers. He shoots dead one of the soldiers named Zar, before getting to the safety of the shelter. However, the soldiers discover the trapdoor and begin to pour in. Grayson & Kemmer throw a grenade into the corridor to try to halt them, though Lora and Galen protest. The shelter has an emergency exit, which most are able to make use of, but Grayson and Kemmer grab Lora, intending to use her to influence her father, Senator Sallus. They escape, leaving Galen, Virdon, Kovak, Black & Aro behind.
The captured group are brought before Zauis, Ursus and the Council and accused of being terrorists. As they deliberate, Senator Sallus bursts in with a ransom note he has received from the UFF. Virdon and Galen offer to negotiate Lora's release, while Kovak, Aro & Black must remain as hostages under the threat of execution. Virdon had recognized Grayson's description of the secret UFF headquarters as being a 20th-century NASA research center, and they travel to the 'Blasted Zone' where they see the irradiated barren wasteland beyond. They continue to the UFF headquarters, where they are questioned by Grayson, Kemmer and Katrin. Lora is unharmed and has come to believe the kidnapping ruse is necessary. Grayson proposes even tougher threats and a note is sent to the Council demanding weapons and safe passage in exchange for Lora's life. Zaius agrees to Ursus' demand to execute one of the hostages in reprisal. Senator Sallus and his wife Clia visit Kovak in his cell to question him, and he suggests relaxing the curfew laws as a means to freeing Lora. Kovak also asks them to try to stop any executions, but from his cell window the following morning, he witnesses the execution of Black.
Virdon is asked to examine the ancient-but-futuristic weapons found at the UFF base, as both he and Galen are encouraged to join the movement. Virdon makes many repairs to a laser weapon, but to his surprise Katrin urges him to destroy it, revealing that her husband was killed by Ursus' soldiers two years earlier while seeking a peaceful resolution. They kiss. Meanwhile, despite Lora criticizing Galen's reluctance to accept violence as a means of change - "You're so full of liberal, middle-class prejudices!" - they too begin to fall in love. However, Grayson and Kemmer are furious on hearing of Black's execution, and they sieze Lora, intending to carry out their threat and match the execution "life for a life". As the ape Council order Kovak to be executed the following morning, Virdon and Katrin plot a way to lead the UFF members against Grayson, but they are overheard by Kemmer. They hoped to distract Grayson while others freed Lora, but as Virdon goes to retrieve the still unfinished laser weapon, he is surprised to find Grayson and Kemmer waiting for him. He runs to warn the others, who have by now freed Lora. Grayson and Kemmer pursue Virdon and corner all of the renegade UFF members, aiming the defective laser weapon at them. It explodes, killing Grayson and Kemmer. In the aftermath, Lora, Galen and Virdon make their way back to the city, where Kovak is allowed to go free in accordance with their arrangement. Katrin and the rest of the UFF survivors have moved on beyond the Blasted Zone to begin a new life of peace and equality. The fugitives head off on their own journey, knowing that they will be hunted once again now that the terms of their agreement with the Council have been met.
Although the script provided plenty of action while staying within the parameters of the TV Series outline, the episode remained unfilmed. That may have been due to the series' cancellation. The episode was also, however, far more political and violent than was seen in the broadcast episodes, and the background information attributed to Galen doesn't fit entirely with his established back-story; one of the main points of the pilot episode was that Galen was a young chimp who had never even considered humans worthy of any great thought, yet in this episode he had a previous history as a free speech activist.