Upon meeting with the time traveler, Rufus, Bill and Ted are given access to a telephone booth that acts as a time machine. They use this machine to travel through different eras in history, collecting historical figures like Napoleon Bonaparte, Socrates, and Joan of Arc to bring back to their present day for their history report.
Along the way, they encounter various obstacles, such as losing Napoleon at a waterpark and accidentally leaving Socrates at a shopping mall. They also face a dilemma when they realize that they must time travel back to a specific moment in time in order to secure an important historical artifact that will aid them in their report.
Eventually, they gather all of the historical figures together for their report, but encounter opposition from their skeptical history teacher who questions the validity of their methods. However, the success of their report and ability to accurately depict historical figures impresses their teacher and they successfully pass their history class.
The film ends with Bill and Ted performing a triumphant rock concert that unites the entire world and brings about world peace.