Lying flat on his stomach, held aloft by a pole extending 20 feet from the ground below, Joaquin Phoenix is giving it his best Superman impression, right arm held straight out in front of him and all. It’s the final day of main-unit shooting on Buffalo Soldiers, and Phoenix, wearing a gray U.S. Army T-shirt and shorts—no cape—is goofing off in front of the green screen for the benefit of his director, Gregor Jordan (Two Hands), who is trying to film the movie’s opening dream sequence. Actually, Phoenix has done this shtick before. “I was in a TV show where I dreamt I was Superboy,” he says later, speaking about his part in The Adventures of Superboy. “I had on the costume and flew on wires. I was, like, ten years old.”

Now 26 and a major star thanks to Gladiator and Quills, Phoenix has spent the past few months on an abandoned U.S. Army base in Germany, playing soldier—a Sgt. Bilko type, who’s out to make a fast buck in any way possible. Only the arrival of the psychotic Sgt. Lee (Scott Glenn) and his daughter (Anna Paquin), for whom Phoenix’s character inevitably falls, can deter him from his illicit money-making operations—drug manufacturing, arms dealing, floor cleaner sales—which continually confound his strict Army camp director (Ed Harris). “He’s just a total shit,” says Phoenix, down from his perch and drawing on a Marlboro Light. “But it’s not really out of malice. If anything, he’s just selfish. I love that he has ruined and saved lives throughout the course of the story, all kind of unintentionally.”

A subversive comedy in the tradition of such antiwar classics as M*A*S*H and Catch-22, Buffalo Soldiers (a name that refers to the African-American soldiers who served in the Old West) is based on a 1993 novel by Robert O’Connor. The $15 million film focuses on a fictitious handful of the tens of thousands of U.S. troops who were stationed in the former West Germany just prior to the fall of the Berlin Wall, in 1989. Some of the soldiers, Jordan learned, experimented with drugs to stave off boredom, and they even shot heroin while driving tanks on maneuvers. “A lot of the stories didn’t make it home to America,” says the director, whose father and grandfather were in the military, and who was raised on air force bases in Australia. “A lot of the research we had was from European newspapers, stuff like ‘19 people die in the latest NATO war games exercises, including six civilians.’ One woman was run over by a tank as she was walking across the road.”

Such atrocities aside, Phoenix found the soldier’s life remarkably easy to grasp. “There were 20 guys [staying] in this little hotel in this small town in Germany, and there was that genuine sense of frustration and boredom.” He smiles. “Our hotel became the barracks.”