Directed by Frank Poulsen 12A cert, QFT, Belfast, 82 min

THIS DOGGED documentary begins with an unavoidable staple of the genre. Danish director Frank Poulsen is trying to secure an interview with a corporate bigwig. You know how this goes. He gets fobbed of by Jobsworths. He expresses exasperation while lurking in the firm’s gleaming lobby. He adopts a tone of outraged surprise. Ya, ya.

That cliché noted, Blood in the Mobileis to be recommended for its rigour, its bravery and (the film does emerge from Scandinavia, remember) its cautiously expressed anger.

The subject is the mobile phone industry. The technology relies on a mineral called coltan, much of which is obtained via a class of slave labour in the Democratic Republic of the Congo. The film argues that our addiction to the ubiquitous devices has helped finance murder, political disorder and uncountable cases of sexual violence.

Poulsen elects to focus his attentions on Nokia, a company that boasts about its caring approach, and he does eventually secure an interview with the company’s head of “social responsibility”. That official comes across as a reasonable man. But one gets the sense that the battle over market share remains more pressing than the need to protect African child workers.

Before that chat reaches the screen, we watch as Poulsen travels to Africa and encounters scenes ghastly enough to occupy one of Joseph Conrad’s more depressing novels. He goes down a mine. He talks to witnesses of the security force’s violence. The film offers an impressive blend of grisly outrage and sober analysis. A few of the sequences in the Congo lean towards the sensational, but such adventures are balanced by careful consideration of possible solutions.

Aside from highlighting a particular issue, Blood in the Mobilereminds us of a more general, easily-overlooked truth. The continuation of our sleek digital existence depends on bloodied men hacking away at rocks in horribly dark holes. This is still a medieval planet.