Boom Town (1940)

Buddies Big John McMasters and Square John Sand are fast-talking, wisecracking wildcatters who manage to con enough equipment and capital to develop their own oil fields, but their friendship is put to the test when Big John inadvertently falls in love with Elizabeth, Square John's longtime girlfriend. Eventually their friendship and partnership comes to an end on the flip of a coin. Years later, when Big John's interest in the beautiful Karen Vanmeer threatens his marriage too, Square John intervenes in an effort to save the marriage of his former friend - even if it means ruining him financially.