Tom Toms of Mayumba

Set in the Belgian Congo in 1925, the narrative follows Dr. Carlo Leonardi (Charles Vanel), a dedicated medical researcher who has spent years combating a severe epidemic of sleeping sickness decimating the rural populations. The sanitary crisis deteriorates drastically due to the reckless actions of his younger assistant, Dr. Assar (Paul Müller), whose unauthorized, experimental medical treatments result in the deaths of several native patients. In response, local tribal drums spread warning messages from village to village that the white physicians' medicines are lethal, inciting a widespread regional revolt against the colonial medical outpost.

Compounding the crisis, an illicit, large-scale alcohol and ivory smuggling ring begins operating within the territory, actively undermining the physicians' authority by distributing black-market spirits as a substitute for legitimate medical care. Seeking information on the black market's source, Leonardi approaches Martinez (Pedro Armendáriz), a corrupt Portuguese trader who is the only European in the region capable of translating the native drum signals. Unbeknownst to the medical team, Martinez is the covert mastermind behind the entire smuggling racket and purposefully misleads the investigation.

To bypass the obstruction, Leonardi and his colleague, Dr. Alessandrini (Marcello Mastroianni), journey upriver into the interior jungle to directly inspect the remote settlements. Despite navigating defensive indigenous populations and tactical sabotage orchestrated by Martinez, the medical officers work to uncover the contraband network. The rising domestic tensions trigger a hostile pursuit through the jungle, complicated further by a manipulative local woman, Madalena (Kerima), who leverages her relationships with the region's prominent figures to consolidate power.

• Pedro Armendáriz - Martinez
• Habib Benglia - Gomba
• Jacques Berthier - Clemens Van Waerten
• Kerima - Madalena
• Philippe Lemaire
• Marcello Mastroianni - Alessandrini
• Domenico Meccoli
• Paul Muller - Dr. Assar
• Francine Delore Rhiney - Louise
• Charles Vanel - Carlo Leonardi