When Betty Bets (1917)

The rich uncle of "Hopeful John" objects to Betty's sister Mabel's upcoming marriage to his nephew, as he considers the family--especially Betty--to be lazy gold-diggers. Betty bets him that she can make $1000 in 30 days. If she can't then Mabel won't marry his nephew, but if she does then he has to give his consent to the marriage. The uncle takes the bet, not knowing that Betty has a plan up her sleeve to not only win the bet but to make the uncle pay her the $1000 she is supposed to make.