In 2285, Maltz participated in Kruge's attempts to obtain and exploit the Federation's Genesis technology. Maltz was present during the destruction of the USS Grissom in orbit of the Genesis Planet, and was the only crewmember left aboard Kruge's Bird-of-Prey when Kruge beamed to the surface to confront James Kirk. Maltz was later taken prisoner by Kirk and his crew, who commandeered the Bird-of-Prey after Kruge's death. When Kirk presented an ultimatum to Maltz to either assist them or be killed, Maltz simply responded, "I do not deserve to live," to which Kirk replied, "fine, I'll kill you later." After successfully escaping the destruction of the Genesis planet, Kirk ordered Maltz imprisoned, an act which surprised Maltz, as he was expecting Kirk to kill him. When Maltz confronted Kirk with his earlier promise, Kirk simply said, "I lied." (Star Trek III: The Search for Spock)
Maltz was played by actor John Larroquette. It is unclear what became of him after Kirk took the Bird-of-Prey to Vulcan. He may have become a Federation prisoner of war, though the Klingon Ambassador makes no mention of him when demanding Kirk's extradition in Star Trek IV: The Voyage Home.
In The Klingon Dictionary, Maltz is credited for revealing the Klingon language to the Federation and to Marc Okrand (2nd ed., p. 12). In Star Trek: Enterprise, Vulcans had the language stored in their database from previous contacts and Hoshi Sato was able to translate the language. According to Okrand, Maltz's name is matlh in tlhIngan Hol (The Klingon Dictionary 2nd ed., p. 58).
On the set, John Larroquette referred to his character as "Chocolate."
In the novelization of the movie, it is stated that he committed suicide. In the Genesis Wave series, however, it was revealed that Maltz survived, but was disgraced by his loss of honor, causing him to hide away from Klingon society for several years before the coming of the Genesis Wave. With the Wave, Maltz's life gained a new purpose, and he tracked the wave to its source on a Klingon vessel under the command of Leah Brahms, who had won his respect due to her determination to warn others about the Wave and avenge the death of her husband. Eventually, after becoming separated from the others, Maltz acquired a Template:ShipClass starship which he used to get on board the asteroid base that was preparing to launch a second Genesis Wave. There, accompanied by Carol Marcus, he set the station to self destruct, regaining his lost honor as they prevented the Wave from ever being used again.