The Broadway Gallant (1926)

Young heiress Helen Stuart is engaged to Monty Barnes, a restless young man. Since Helen is not yet 21, her estate is controlled by her guardian and uncle, Jack Peasley, who is not above using Helen's money for his own purposes. He takes a large chunk of her money to buy a block of railroad stock, that turns out to be worthless. Red Sweeney, who sold him the phony stock, assures him that if Helen marries before she turns 21, she'll never know the money's missing because the estate will revert to him, as her guardian. They force her to marry Monty, who is unaware of their scheme. Complications ensue.