The movie begins with a young John Watson arriving at the boarding school and meeting a teenage Sherlock Holmes who is already renowned among his peers for his intelligence and observations. Initially, Watson is skeptical of Holmes's abilities, but soon they become friends after Holmes saves him from a group of bullies.
Soon after, they stumble upon a strange murder that they believe is linked to an ancient Egyptian cult known as the "Rame Tep." As they investigate the case, they meet a beautiful young woman named Elizabeth who is also investigating the cult, and they team up to unravel the mystery.
Their investigation takes them to an underground temple where they encounter the leader of the Rame Tep, who is using a secret potion to control and manipulate the minds of his followers. The cult leader captures Elizabeth, and Holmes and Watson must brave dangerous traps and challenges to rescue her and stop the cult from carrying out their deadly plan.
In the end, Holmes saves the day using his incredible deductive abilities, and the trio becomes lifelong friends. The film ends with Watson heading off to war and promising to write to Holmes, thus setting the stage for their future adventures together.