Star Trek The Original Series Rewatch: "And the Children Shall Lead"
Stardate: 5029.5 Captain’s log. Kirk, Spock, and McCoy beam down to Triacus, a scientific outpost, responding to a distress call. They materialize to find a whole lot of dead bodies. There’s only one survivor: Professor Starnes, but he dies after a minute, and he doesn’t recognize Kirk before he croaks. One of the corpses has a bottle of poison in her mouth, and Starnes’s last log entry on his tricorder indicates that they have to all kill themselves because of the enemy within. (Gee, t...
Source: tor.com