The Omega Glory
Summary
Captain Kirk must battle a deadly virus and a treacherous fellow starship captain to stop a meaningless intertribal war. The Enterprise responds to a signal received from the USS Exeter, which is orbiting a planet but not responding to any communications. Upon boarding the ship, Kirk, Bones, and Spock finds that the crew has disappeared and have left behind clothes and a mysterious salt rich in potassium and carbon. Bones realizes that this could be the remains if the crew's bodies lost all their water. Spock plays the last log from the Exeter and finds a message that says everyone is affected by a virus and should not go back to their ship but beam down to the planet's surface. Upon landing, they find Captain Tracey of the Exeter, but he is fighting a war with the inhabitants on the side of the Yangs.
Summary from Wikipedia, CC BY-SA 4.0.
Find out more
These links open the services in a new tab with the question pre-filled; the AI assistants may ask you to sign in. Their answers can contain errors.