Good documentaries often leave you pondering a question. This investigative doc leaves your mind swimming with unanswered questions. Does Saddam have a nuclear bomb? Has a German neo-nazi conspiracy enabled developing nations, or worse Al-Qaeda, to build nuclear arsenals? Did German industrial giant Degussa knowingly help Iraq develop nuclear weapons?

Part of the problem is that John S Friedman and Eric Nadler's 95 minute investigation covers so much ground - four continents and six decades to be exact - as the filmmakers chase their story from the laboratories of the Third Reich to those of Saddam Hussein.

The way they tell the story also doesn't always clarify. Instead of presenting a synthesised case, the filmmakers give a chronological blow by blow account of how their investigation unfolded. What you get is something like a dossier of leads and ideas that are not always followed through, but that offers plenty of sensational propositions.

The filmmakers five-year project began with a newspaper item about a rogue technician, Karl-Heinz Schaab, who was up for treason in Germany. He had helped Iraq to develop an ultracentrifuge for extracting weapons-grade uranium-255. It was the first such public case in 50 years, and as is successfully posited was as good as swept under the carpet by the German government due to the embarrassing questions it threw up. Schaab was found guilty, but only fined $32,000 (less than he made from selling nuclear secrets) and given five years probation. The doc to some extent explains why there was a white-wash.

The trail begins at Schaab's quiet suburban home in Bavaria. But no Schaab. So Friedman and Nadler interview neighbours who bring out tabloid cuttings about the "Technician of Death" and talk about their "disturbed and insecure" neighbour. Then the filmmakers are tipped off that Schaab has done a runner to Rio. Cue shots of the the Brazilian capital and groovy Samba soundtrack - the music pastiching the spy thriller genre for lightness. Schaab, a grim-faced character in a ludicrous wig, sits in a seedy hotel room and tells us that he is just a scape-goat.

The filmmakers follow the hapless Schaab when, feeling it was safe enough, he voluntarily returns to Germany for trial. We see him in the supermarket and some painful preparations with a hotshot German defence lawyer for his case. Schaab shows little remorse for his actions - he did it for the money - only that he got caught. His lawyer, a philosophical chain-smoker, suggests fatalistically that once the Pandora's box is open you can't put it back. If it isn't Schaab it will be someone else.

At this point, the doc flashes back to the nazi era with the help of copious archive war footage and the centrifuge technology that Schaab was selling is traced through the years to German multi-national Degussa, an organisation who is shown to have profited from the holocaust. The doc shows how Degussa had the exclusive contract to smelt gold from concentration camp victims, manufactured Zyklon-B (used in the gas chambers), supplied uranium for the Nazi atomic bomb project and since the war has sold secrets to developing nations.

So many people - experts, scientists, historians, industrialists, lawyers, journos - are interviewed that there is often only room for a soundbite here or there before we move along. Many of the interviews are startingly candid. "Germany was an open field to us," says the Iranian scientist responsible for building a bomb for Saddam. Scientists and businessmen, involved in what a former SS physicist calls fondly "the game", talk matter-of-factedly about how the tools for weapons of mass destruction were traded on the black market.

At times there seems to be more smoke than fire. However, by the time the filmmakers have come full circle to the end of Schaab's trial, they have joined enough of dots to leave you in little doubt that the "traitor" is a just small fish in a very large, dirty pool.

Questions have been asked. Answers should now be given.