Gravesend uses a documentary approach to focus on the mining of coltan, employed in the manufacture of cell phones, laptops and other high-tech apparatus. The film cuts between two sites: a technological, highly automated industrial plant in the West where the precious metal is processed for the final production of microelectronic parts, and the central Congo, where miners use simple shovels or their bare hands to extract, wash and collect the ore on leaves. IThe realism of the film images is intercut with a black-and-white animation of the Congo River. Its sinuous shape conjures associations with networking and the flow of communications, underscored by a murmuring resembling thousands of voices in the cell phone network. In the meantime, coltan, traded at an extremely high price, represents one of the key financial factors in the armed conflict of the militia in the Democratic Republic of the Congo, where decades of civil war have cost several million human lives.