Task: Question Answering
Input (English): Passage: A wealthy Los Angeles land developer, Monte Peterson, travels to Utah hoping to open a ski resort after his third marriage ends in divorce. He competes against an "evil" banker, Preston Gates, hoping to snatch land from the defaulting farmers to gain control for mob investors who want to build a casino.
After winning a land auction, Monte's friend explains the polygamous traditions of the area. Monte must join the church to purchase the land. He learns the property he has bought includes the former owner's wives, which upsets Monte greatly until he gets a look at the women.
Monte marries all three and is excited until he discovers how difficult it is to please young amorous wives and also how terrible their cooking is. He develops methods to care for them in a fair manner. He learns that one wife is a twin sister to a wife of banker Gates, making Gates his brother-in-law. Gates is in cahoots with a Las Vegas mobster, Tony Morano, who assures him that his armed henchman "Shuffles" will handle matters if Gates does not.
After another resident passes away, Gates attempts to take control of the deceased owner's land along with his two widows by calling in unpaid debts. Monte is reluctant to marry yet again until he sees these two women are extremely skilled in the kitchen, thus he ends up with several more acres of land and two more wives. Monte retires the debt of their first husband, thus once again thwarting Gates, who sought repossession of the mortgaged lands over repayment of the debt.
Gates, frustrated, has his associate Stewart try to catch Monte in the act of smoking or drinking to get him excommunicated from the church and kicked out of town. As a treat, Monte takes his wives for a honeymoon to Las Vegas, introducing them to gambling and other joys of the modern world like tennis and bikinis. 
Question: Who does Gates ask to catch his brother-in-law smoking or drinking?
Output (English): Stewart.