He only appears in The Lost Continent Syndrome. He intends to rise the city of Atlantis, destroying half of the city in the process. His base of operations is within the city itself.
After Agent J and Agent K manage to find his work robots, his battle robot manages to knock them both out. He imprisons K and leaves J "sleeping with the fishes", oblivious to the fact that J now has gills. After being questioned by K, Quintoon admits the hostages are merely a precaution, should MiB attempt to interfere with his plans.
After realizing J is still alive, he sends his battle robot to kill him and manages to start the city's ascent.
Quintoon flees in his small vehicle after J defeats his robot and comes back to free K. It turns out MiB's agent inside the submarine was working with Quintoon and was in charge of stalling MiB by warning about the loss of contact at the last minute. Quintoon's plans are stopped after the agent knocks K unconscious and takes control of the ship, ramming it against the city's supports, sinking it. J apprehends Quintoon soon after.