The final Black Emanuelle collaboration between director D'Amato and actress Laura Gemser is perhaps the most conventional, structurally, of their films together. It still flits madly between genres, like some crazed canary battering its wings against its cage, but it does keep Emanuelle as a central protagonist in a recognisable three act structure, with a single plot going all the way through.
The first half hour takes place in Nairobi, giving D'Amato the chance for some Mondo-like shots of wildlife and tribal ritual. Emanuelle is trying to secure an interview with a European businessman who lives the life of a baron in the country, and we see her infiltrate his defences through cunning guiles and seductions. This first half hour includes a typical soft-core encounter, as Emanuelle's friend and guide gets laid by her garage mechanic in his pit, plus a couple of nifty sexual montages, one interspersing lovemaking with tribal ritual, the other filming a love scene from behind columns, the camera tracking round and the screen going black as it glides behind a post; these two scenes bring into play the usual soft-core soft-soap of sex being associated with primitivism and loss of consciousness. But as usual, D'Amato has bitterer fish to fry, and the first half hour also has Emanuelle witnessing what looks like the trafficking of a woman against her will.
Back in New York, after rekindling her affair with a fashion photographer, Emanuelle does a James Bond and goes undercover into the world of the white slave trade. A striking sequence in a plush hotel has her peaking in on an auction in which young girls are bought like cattle (we share her hidden POV); she then pretends to be a poor girl and is taken up by a trader, put on a sex farm and told to please the rich, powerful old men who go there. The owner, one Madam Claude (a reference presumably to Just Jaeckin's 1977 film of that name), keeps a tight house, forbidding her workers to stray outside of their allotted apartments on her ranch. Of course, Emanuelle strays and discovers that Madam is trafficking very young girls from the ranch to foreign climes. This discovery puts Emanuelle in considerable danger, a danger nicely prefigures by the nervy POV walk we do with her on arriving at the airport to depart for the San Fransico-based farm.
The most intriguing character in the film is Stefan, the burly transvestite duenna at Madam Claude's. Always in drag, he bosses the girls around and seems like Madam's best arm, but despite being cast as a eunuch at a harem, he falls for Emanuelle's charms and sleeps with her. This makes him vulnerable, as when he catches her taking pictures for evidence he decides to help her – but that brings down the wrath of Claude's thugs onto his head, and despite putting up a spirited kung fu fight, he is violently murdered. Stefan operates in a strange position in the sexual politics of the film – he works for what is ultimately patriarchal power, farming girls like cattle for old men, but his emotions and his low position in the food chain feminize him as much as his dress. It is no surprise that a man who doesn't play the male role "properly" finds himself as disposable as the women seem to be in this world.
Emanuelle and the White Slave Trade, like its predecessors Emanuelle in America and Emanuelle Around the World, uses the soft-core genre to ask some hard questions about the darkness sexuality can encompass as well as the commoditisation of women in a patriarchal system. It isn't as gobsmackingly out there as either of those films, but it does move at a steady pace as well as taking its audience into uncomfortable areas around the exploitation of women. It is no surprise that D'Amato made no Emanuelle film after this (except a cynical compilation) as he was beginning to repeat himself, and had darker areas to explore than could be borne by the soft-core genre which he'd taken to its limits.