As Gunter Wallraff, the superstar undercover journalist in Bobby Roth's irritating political thriller "The Man Inside," Jurgen Prochnow doesn't exactly slip into a phone booth and change into tights and a cape, but he might as well.

A champion of all that is good and pure, Wallraff is every journalist's fantasy of the man who breaks the big story, who lays it all on the line and exposes injustice and leaps tall buildings in a single byline. A loner with no weaknesses and no vices, who refuses to affiliate himself with any institution, who works only on spec and with the support of only a handful of friends, Wallraff accomplishes his journalistic miracles with an air of Zen-like detachment. In Europe, where he's made a regular though somewhat mysterious practice of ripping the lid off corporate and governmental corruption, he's both heralded and vilified for his first-person expose's. His enemies, including Germany's sleaziest and most powerful daily, the Standard, are out to get him. But learning of the paper's disturbing connections with an extremist government official, Wallraff decides to turn the tables, infiltrate its operation and expose them.

Roth reaches his most absurd heights in detailing the daily activities at the paper. The Standard specializes in a kind of pit-bull-style of journalism; think of the New York Post on its worst day. Its editor and spiritual architect is a strutting martinet named Schroeter (Dieter Laser), who bellows at his staff like a deranged Nazi commandant, urging them to go for the jugular. He wants blood in the pages of the Standard, and nothing -- slander, invented quotes, doctored photographs -- is too extreme.

Wallraff, quite naturally, is far too sensitive not to be polluted by these vicious, conscienceless scribes. Gradually his soul starts to shrivel, a state of mind that, as Prochnow conveys it, appears close in nature to heartburn. Even though he feels his values are being compromised, he can't bring himself to drop his investigation. "I am on the inside," he tells his girlfriend (Nathalie Baye). "They are inside you," she retorts.

Roth, who wrote the script as well as directed, makes a hash of the narrative and his themes. As a political thriller, it has virtually nothing to say, and what it does say is laughable. The only fun here comes from the grotesquely mannered performances of Laser, who glowers like Hammer horror-film vampire, and as the Standard's star reporter, Peter Coyote, who somehow manages to be ludicrously, floridly German while at the same time never once allowing us to forget he is an American actor being ludicrously, floridly German. Coyote's touch of irony almost elevates the production to the level of camp. Almost.

The Man Inside, at the Key, is unrated.