Alva is a class M planet, the second planet in the Edison II star system. It was named after the famous American scientist, Thomas Alva Edison.
Alva housed a Terran commercial colony, which was started by an investment group on Earth sometime between the 2220s and 2230s.
In the late 2260s, Pat Bradley, Montgomery Scott, Leonard McCoy, and Spock of the USS Enterprise beamed down to do a routine check on the colony for medical supplies and technology. The away team was ambushed by a squad of Klingons, led by King Klandor. Klandor planned a takeover by beaming aboard the Enterprise with Spock.
The invasion was thwarted, however, due to the intervention of an "angel", who held Spock and Klandor in limbo in another dimension. The angel turned out to be a small, childish shapeshifting creature who only wanted the two as a means of entertainment. Once they were returned to normal space, Spock was able to recover before the Klingon boarding party and rendered them unconscious with a Vulcan nerve pinch. The Klingons were then placed in a prison on the planet's surface. (Star Trek III Short Stories - A Vulcan, A Klingon, and an Angel)