The Gauntlet (1977)

In Phoenix, Arizona, alcoholic and mediocre Detective Ben Shockley (Clint Eastwood) is assigned by Chief Commissioner Blakelock (William Prince) to bring witness Gus Mally (Sondra Locke) from Las Vegas, Nevada for a minor trial.

Shockley travels to Las Vegas and finds that Gus Mally is an aggressive and intelligent prostitute with a college degree and she tells him that the odds are against her showing up in court. Shockley learns that she will actually testify against a powerful mobster, and the mafia is chasing them, trying to kill them both. He calls Blakelock and requests a Police escort from Phoenix to protect them. But soon, he discovers that someone is betraying him in the Police Department. Now, Shockley and Malley hijack a bus and Shockley welds thick steel plates and transforms the cabin in an armored bus trying to reach the Forum. But they will need to drive through a gauntlet of Police Officers armed with heavy weapons.