In the 1960s, someone released the Nile perch into Lake Victoria as an experiment. The fish thrived, wiped out hundreds of native species, and turned into a global export business, and Hubert Sauper's camera follows what that business actually looks like on the ground in Tanzania. Russian cargo pilots land at Mwanza airport, officially to move fish fillets to European supermarkets, while rumors and half-seen crates suggest they are also running weapons into nearby war zones. Filleting-factory workers breathe fumes off the rotting perch carcasses left behind for local consumption, street children sniff glue melted from fish-packing plastic, and a night watchman explains why he prefers guarding the plant to fighting in a war. Sauper interviews pilots, factory owners, prostitutes, priests, and a local journalist trying to report on the arms allegations, letting each account complicate the last. The film never states a thesis so much as accumulates evidence: a lake full of profitable fish, a country getting poorer beside it, and a supply chain that connects both to a Europe that never appears on screen.