"Supreme Leader" centers on small-town go-getter Steve Loomis (Dillahunt), whose dream of becoming "supreme ruler" of his local Buffalo Lodge is unexpectedly challenged by a hard-drinking, womanizing lodge member, Hank. The two men are forced to travel to the Buffalo National Convention in Chicago in order to win the support of the organization's national leaders, where Steve befriends an established supreme ruler, Nancy (Lewis).