Writer and notorious marriage detractor Mortimer Brewster (Cary Grant) falls for girl-next-door Elaine Harper (Priscilla Lane), and they tie the knot on Halloween. When the newlyweds return to their respective family homes to deliver the news, Brewster finds a corpse hidden in a window seat. With his eccentric aunts (Josephine Hull, Jean Adair), disturbed uncle (John Alexander), and homicidal brother (Raymond Massey), he starts to realize that his family is even crazier than he thought.