The story begins with Butch Gorman and Brent Kirby, partners in a detective agency, discussing the perilous state of their office location. They anticipate the arrival of their client, Colonel John A. Pembroke, a mysterious and wealthy figure. As they prepare for the meeting, a violent incident below their office leads them to discover Pembroke attacked and barely conscious. Pembroke suspects someone from his hidden past is trying to kill him and hints at a long-standing vendetta against him.

As Kirby and Gorman delve deeper, they uncover elements of Pembroke's past involving a treasure linked to an ancient Egyptian artifact, the "Necklace of Balkis," rumored to have mystical properties. Pembroke, under the alias John Ravenby, had made many enemies during his time in Africa, involving himself with notorious figures and participating in the colonial exploitation of resources and people.

The narrative tension escalates when the detective duo decides to protect Pembroke, who is increasingly paranoid about being assassinated. Throughout the night, they fend off mysterious attackers and try to piece together Pembroke's fragmented confessions about his past. The plot thickens with the arrival of Richard Stalbridge, a descendant of a man wronged by Pembroke, who also claims a right to the cursed treasure.

The climax is a violent confrontation in Pembroke's mansion, involving all parties entangled in the deadly game for vengeance and redemption. The detectives struggle to protect their client as layers of betrayal and the true nature of the treasure come to light, culminating in a chaotic and bloody showdown.