Jack Sadelstein (Adam Sandler), a successful advertising executive in Los Angeles with a beautiful wife (Katie Holmes) and kids, dreads one event each year: the holiday visit of his identical twin sister Jill (also Adam Sandler). Jill’s neediness and passive-aggressiveness drive Jack crazy and turn his normally tranquil life upside down. Things spin even more out of control for Jack when Jill decides to extend her visit--and he starts panicking that she’ll never leave.