The story unfolds as Kirby encounters a mysterious, imposing man of Oriental appearance in the hallway of his office building. This man cryptically warns Kirby against interfering in matters that do not concern him and hints at a sinister object left in his office. Kirby discovers a dead man in his office shortly afterward, initiating a complex tale of mystery and danger.

The dead man is identified as William Harper, leading to Kirby's involvement with Gloria Corwell, who reveals a perilous situation at her uncle Richard Corwell's manor, besieged by a group of menacing, foreign men after a man named Farnum. Farnum, a rogue adventurer, had returned from India with a secret treasure, drawing the wrath of a dangerous cult.

Kirby, Gloria, and Kirby's partner Gorman end up at Corwell Manor, where they face continuous threats from the cult, identified as the Thugs, devotees of the goddess Kali. The situation escalates as they try to protect the manor against these relentless attackers who are intent on retrieving the treasure Farnum stole.

In a dramatic confrontation, Farnum reveals that the treasure includes the legendary jewels of Akbar, hidden under an old temple in India. He confesses to murdering a man to escape with the jewels, leading to a fallout with his former partner Ditta Ram, a disreputable Brahman leading the Thugs.

The narrative climaxes in a violent showdown at the manor, where Kirby, Gorman, and the Corwells defend themselves against a night-time assault by the Thugs. The situation seems hopeless until the arrival of the Sons of Akbar, another group also interested in the jewels, who intervene to resolve the conflict.

The story concludes with the Sons of Akbar reclaiming the jewels and departing, leaving Kirby and his companions to recover from the harrowing ordeal. The peace is restored, but the shadows of the night's events linger, leaving a deep impact on all involved.