Firefly first appeared on his motorcycle which had a Cobra symbol while using miniature robotic fireflies (hence his name) to break out Cobra Commander from prison along with Storm Shadow. He is later shown greeting his boss and retreating to a new Cobra base. Later on, he greets Zartan and discusses the Commander's new evil plan henceforth Project Zeus, which launches several Cobra satellites and destroys a city in a different corner of the world.
His next scene is when he encounters former fellow Joe Roadblock, who is investigating along with the other GI Joe survivors about who the President really is (being Zartan).
His next scene in the film is when he works with Cobra Commander to take control of the world leaders through Project Zeus, only to be foiled by Storm Shadow (who allies with the Joes to avenge his uncle's death at the hands of Zartan). Later on, after the GI JOEs infiltrate the World Leaders summit, Firefly escapes with the Project Zeus briefcase and prepares to flee the Presidential retreat, only to find himself in one final confrontation with Roadblock, who fights him for control of the briefcase. He faces defeat after Roadblock retrieves the case. His death here is shown when he tries to launch a firefly drone at Roadblock, only to find himself blown to bits when Roadblock uses Firefly's drone device. He was never seen again after that.
Firefly is a sadistic psychopath and a pyromaniac who enjoys inflicting harm or death upon others, preferably through explosives. He also comes off as a sadistic, cruel bully as he inflicts punches and blows on both Roadblock and the true U.S. president for his own amusement. Cobra Commander who took interest in his expertise in pyrotechnics appointed him as his third-in-command even if Cobra Commander saw Firefly as childish and hyperaggressive. Zartan expressed disgust and contempt for Firefly's short temper, as Firefly would get angry about even the smallest things like federal tax hikes when he never pays taxes.
To prepare for his role as Firefly, Ray Stevenson read the G.I. Joe comics. He became a fan of his character, even putting in his own money so that the costume designers would make a mask to go with the costume.