 When a prototype helicopter with capabilities that could rival even Airwolf is stolen from a military compound, String suspects that his brother just may be involved. He confronts the people that he believes are responsible and discovers that Mace Taggert (Sam Melville), another man who was supposedly imprisoned with his brother and presumed dead, is alive and well and responsible for stealing the chopper. Taggert and his mercenary buddies plan to sell the copter to the highest bidder, but when the HX1 takes on Airwolf, the buyers get to witness a showdown that they will never forget.