'The Deadly Years' by David P. Harmon

While en route to Starbase 10, the U.S.S. Enterprise delivers supplies to the colonists living on the planet Gamma Hydra IV. However, when Captain Kirk and a landing party beam down to the surface, Ensign Chekov is shocked to discover a wizened cadaver; after further investigation they find that every one of the colonists has died from extreme rapid aging. Kirk and the others return to the ship, but they too have become infected, and soon the entire crew begins to increase in age - except for Chekov, who inexplicably remains completely unaffected. Kirk decides to remain in orbit around the planet until Doctor McCoy can find a cure, but Commodore Stocker is determined that the ship continue on to Starbase 10 so that they can receive the best medical assistance available. It is not long before Kirk's increasing age leaves him unable to command the ship, and Lieutenant Commander Spock and Chief Engineer Scott are also incapacitated. The younger Commodore Stocker takes control of the Enterprise, but his lack of deep space training leads him to set a course through the Romulan Neutral Zone in order to save time on reaching their destination - and the Enterprise is quickly surrounded by attacking Romulan ships...

William Shatner (Captain James Tiberius Kirk), Leonard Nimoy (First Officer Lieutenant Commander Spock), DeForest Kelley (Doctor Leonard H. ‘Bones’ McCoy), James Doohan (Chief Engineer Montgomery ‘Scotty’ Scott), Nichelle Nichols (Lieutenant Nyota Uhura), George Takei (Lieutenant Hikaru Sulu), Walter Koenig (Ensign Pavel Andreivich Chekov), Charles Drake (Commodore Stocker), Sarah Marshall (Doctor Janet Wallace), Majel Barrett (Nurse Christine Chapel), Felix Locher (Robert Johnson), Carolyn Nelson (Yeoman Doris Atkins), Laura Wood (Elaine Johnson), Beverly Washburn (Arlene Galway)

Directed by Joseph Pevney

TX:
8th December, 1967

Notes:
*Featuring Captain James Tiberius Kirk, First Officer Lieutenant Commander Spock, Doctor Leonard H. ‘Bones’ McCoy, Chief Engineer Montgomery Scott, Lieutenant Nyota Uhura, Lieutenant Hikaru Sulu, Ensign Pavel Andreivich Chekov and Nurse Christine Chapel