A planet with red inhabitants. Apparently, the fifth moon of Mixtus III (which was scheduled for demolition) was key in blocking the pollution of Mixtus III from reaching Mixtus II, and its demolishment would result in the death of everyone on this planet.
This, however, turned out to be only two people: a rich married couple who had bought the entire planet.
Captain Durango was the commanding officer of the U.S.S. Merced in 2380. He was Tellarite, and had served with Captain Carol Freeman on the U.S.S. Illinois before they both achieved their own commands. The two were then paired together on a mission involving the towing of an ancient generation ship.