The story begins with the protagonist being approached by a terrified houseboy, Agadi, who informs him that his neighbor, John McKerr, has been murdered. McKerr's body is found near the river, with a spear in his back and a vampire bat wing nearby—an ominous symbol of voodooism. The protagonist, along with his companion Ahmed, buries McKerr and begins to investigate the murder, suspecting witch doctors but finding no concrete evidence.

As tension rises among the local tribes, the protagonist and Ahmed encounter a formidable witch doctor named M’Nungo-wayo. This man exudes power and malevolence, instantly causing unease. After a confrontation where Ahmed tries to kill M’Nungo-wayo but fails, the witch doctor vanishes, and soon after, more murders occur, including the gruesome deaths of the protagonist’s friends, William Mell and Clev Cornage, each marked by the sinister bat wing.

The protagonist becomes increasingly paranoid and wary, anticipating an attack. One night, he is lured into the jungle by his seemingly loyal houseboy, Membula, under the pretense that Ahmed needs help. Sensing a trap, the protagonist kills Membula when his suspicions are confirmed. However, he is then captured by a group of natives and taken to a secret voodoo gathering where he is to be sacrificed.

In a sacrificial chamber, the protagonist finds himself in a horrifying situation, surrounded by skulls and blood. He fights off an attacker, kills him, and escapes through a trapdoor, only to face a gigantic python in a pit. Just as he faces certain death, a rescue party led by Ahmed, the Zulu chief Umslopogas, and Captain Oldwick of the Rhodesian Royal Police arrives, killing the python and dispersing the natives.

Ahmed explains that M’Nungo-wayo had been stirring up the tribes, aiming to unite them under his control using voodoo and terror. M’Nungo-wayo's ultimate goal was to overthrow the colonial rulers and establish his own power. The rescue party, aided by Umslopogas and his warriors, thwarted this plan just in time. The story concludes with Ahmed presenting the severed head of M’Nungo-wayo, with a bat wing in its mouth, as proof of their victory.