The Gauntlet

In Phoenix, Detective Ben Shockley is tasked by Chief Commissioner Blakelock with bringing witness Gus Mally from Las Vegas for trial. Shockley discovers Mally is a street-smart prostitute willing to testify against a powerful mobster. As they flee, Shockley realizes they're being betrayed by someone in the police force. They hijack a bus, reinforce it, and attempt to reach the court while being pursued by armed police officers.