Clint Eastwood stars along with Shirley MacLaine as a drifter and a nun who join up with Mexican freedom fighters. It was filmed entirely in Mexico.

In one memorable sequence, our heroes sabotage a railroad bridge sending the train flying off. For this scene, a full-scale mockup was created of FCI #67 (the real one was seen in The Magnificent Seven). Today the real-life locomotive is safe and sound on display at the La Villa Station Railroad Museum in Mexico City.