Joe Friday, a strait-laced and by-the-book Los Angeles detective, is paired with a laid-back and unconventional partner, Pep Streebek, to investigate a series of bizarre crimes. Their first major case together involves the theft of a large shipment of chemicals, which leads them to uncover a secret pagan cult called P.A.G.A.N. (People Against Goodness and Normalcy). As they dig deeper, Friday and Streebek discover that the cult is planning a citywide crime spree and that their activities are far more sinister than initially thought.

Their investigation brings them into contact with a colorful array of characters, including Connie Swail, a young woman who becomes an essential witness, and Reverend Jonathan Whirley, seemingly a pillar of the community with a hidden agenda. Together, Friday and Streebek must navigate bureaucratic challenges and physical dangers, combining their contrasting styles to thwart the cult's plans. Along the way, they learn to appreciate each other’s methods and develop a begrudging respect, realizing that teamwork is key to solving the case and restoring order to Los Angeles.