Two Mules for Sister Sara (1970)

Synopsis
Director Budd Boetticher wrote the story upon which this comic Western was based. Clint Eastwood stars as Hogan, a tough cowboy who rescues a woman, Sara (Shirley MacLaine) as she's about to be attacked by a trio of rapists. Surprised to learn that his new traveling companion is a nun, Hogan agrees to escort her to a camp occupied by anti-French revolutionaries. It turns out that neither of this pair is what they claim to be: Hogan is to scout out a French military garrison for a future attack, while Sara is actually a prostitute masquerading as a nun. After Hogan spies Sara smoking cigars and drinking whiskey, he begins to figure out she's not a bride of Christ, and the two team up with the Juaristas to destroy the French fortifications. ~ Karl Williams, All Movie Guide