British army sergeants Ballantine, Cutter and MacChesney serve in India during the 1880s, along with their native water-bearer, Gunga Din. While completing a dangerous telegraph-repair mission, they unearth evidence of the suppressed Thuggee cult. When Gunga Din tells the sergeants about a secret temple made of gold, the fortune-hunting Cutter is captured by the Thuggees, and it's up to his friends to rescue him.
After young Mary Gibson discovers that her older sister Jacqueline has disappeared, she leaves her boarding school and heads to New York City to track down her sibling. But Mary gets drawn deeper into the mystery.
Captain Stone's newly recruited officer, Tom Merriam, idolizes his senior who treats him like a friend. But when a couple of his crew members die mysteriously, Tom starts doubting Stone's authority.
