The two "O'Leary" brothers grow up without their father in an house where their widowed mother runs quite a successful laundry business. One son, "Jack" (Don Ameche), shows promise as a lawyer; the other "Dion" (Tyrone Power) is a more inventive sort of fella. After a few, quite entertaining wooing antics, the latter hooks up with visiting chanteuse "Belle" (Alice Faye) and together they start a business that rapidly expands so as to soon dominate the rather rundown "Patch" area of Chicago. The city government is riddled with corruption and so a group of civil libertarians nominate brother…