Oh! Susanna is a "big" western by Republic standards, decked out with lavish production values and an extended running time (90 minutes, as compared to the usual "B"-picture length of 60 or 70 minutes). Rod Cameron stars as Captain Calhoun, a cavalry officer dedicated to protecting the rights of Indians from greedy gold prospectors. Calhoun's superior officer Lt. Col. Ungar (Forrest Tucker) despises all Indians, and makes things difficult for those who try to enforce existing treaties. Other interested parties include saloon owner Ira Jordan (Jim Davis), who is counting upon plenty of revenue from the prospectors, and saloon thrush Lia Wilson (Adrian Booth), who carries torches for Calhoun, Ungar and Jordan. The highly anticipated action climax comes with a vengeance as the betrayed Indians lay siege upon Ungar's fort. Oh! Susanna was written by Charles Marquis Warren, whose later TV work included Wyatt Earp, Gunsmoke and Rawhide.