Diana McQueen notorious con-woman has had enough. She leaves town and her boss, Tom Rourke, behind. She takes the place of her dying friend, who was to become some man's mail-order bride. Can she pull off this last con?

Joey Drayton brings her fiancé, Dr. John Prentice, home to sunny San Francisco to meet her affluent parents. Their liberal persuasions are now put to the test, for although the young man is an ideal choice (he's highly and internationally respected in the medical field, and he's impeccably mannered, handsome, well dressed and of a respectable California family), he's black. The film, which covers one busy day in the Drayton home, is essentially a drawing-room comedy, a series of cross-conversations between the young doctor and the girl's parents, and finally between all sets of parents and offspring. A simple dinner is extended to include the doctor's parents, who fly up from Los Angeles for the evening, and the crusty but benevolent old Irish priest, a friend of the family. Thus, the title of the film . . .

The siblings Noah and Emma travel with their mother Jo from Seattle to the family cottage in Whidbey Island to spend a couple of days while their workaholic father David Wilder is working. They find a box of toys from the future in the water and bring it home, and Emma finds a stuffed rabbit called Mimzy, and stones and a weird object, but they hide their findings from their parents. Mimzy talks telepathically to Emma and the siblings develop special abilities, increasing their intelligences to the level of genius. Their father becomes very proud when Noah presents a magnificent design in the fair of science and technology, and his teacher Larry White and his mystic wife Naomi Schwartz become interested in the boy when he draws a mandala. When Noah accidentally assembles the objects and activates a powerful generator creating a blackout in the state, the FBI arrests the family trying to disclose the mystery. But Emma unravels the importance to send Mimzy back to the future.