Eric Knox is a scientist whose expertise in voice recognition software created a signature product allowing computer systems to map and identify voices to people, similar to fingerprinting. When Knox is kidnapped and his software is stolen, Knox Industries president Vivian Wood hires millionaire Charles "Charlie" Townsend and his elite team of three female private investigators - Dylan Sanders, Natalie Cook and Alex Munday, or "Charlie's Angels", to find Knox and retrieve the software. Wood points them towards Roger Corwin, the owner of Red Star Systems, who recently attempted to purchase Knox Industries.
The Angels find him tied to a chair in a dark room and return him back to the agency for safety. Knox describes to the angels about his software that was stolen, as Wood mentions Audio D.N.A which makes it impossible to disguise a voice. After the Angels plant a hidden camera on Corwin's briefcase to spy around Red Star. Charlie reports to the Angels that his software is at Red Star's Technologies, Corwin's business.
Meanwhile, the Angels manage to get the Software back and report it back to John Bosley at the agency. Worried about Knox's safety, Dylan says that she would love to stay at Knox's house to protect him. Knox and Dylan later have a nice relationship growing at his house. Natalie is going out with her new boyfriend Pete and Alex is at home thinking of a way to tell her lover, Jason Gibbons, that she is an Angel.
While at his house, Knox shows a picture to Dylan of his father and a man whose face is covered up who supposedly killed his father. Later, Dylan becomes greatly involved in Knox. But later Natalie calls Dylan about how Vivian Wood sent an assassin to kill her and tells Dylan to warn Knox. Alex and Natalie meet up at the agency and Alex has also attempted to have been killed.
After Dylan tries to warn Knox, Vivian Wood reveals herself at Knox's place to Dylan and the Thin Man appears after killing Corwin. Later Knox reveals himself to be the mastermind and tells her of how he had kidnapped and drugged Bosley. He tells her of how the kidnapping was a setup and how he wanted the Angels to break into Red Star to track Charlie and kill him because he thinks Charlie was the man who killed his father. He shoots at her after which she falls out of the window. He, Vivian and the Thin Man go to the lighthouse where they keep Bosley captive.
As the Angels all have survived they come for the lighthouse. As Eric is working to find Charlie, Dylan confronts him. He and Vivian quickly capture him, and they send thin man and their men to find the other angels. Teasing a tied up Dylan, Vivian goes after Natalie and the Thin Man fights Alex. Knox orders his men to get rid of Dylan as he leaves for the chopper. Using the chopper Knox fires a missile at the Angels presumably killing Vivian and the Thin Man. While Knox is flying to Charlie's home the Angels arrive to his helicopter while Alex is trying to disable the missile and Dylan is attempting to finish off Knox with Natalie helping Alex. After Knox's last rocket has been fired, Natalie disables the control as it misses Charlie and fires back and kills Knox while the Angels jump to safety.
- Initially, Knox has a mop top to signify his charming, boyish persona. When his true nature is revealed, his hair is slicked back.
- Although Charlie explained that Knox's father was killed on the other side for being a double agent, it was never known why Knox believed Charlie betrayed him.