Hayley Mills played a double role in this hugely popular romantic comedy as twins Sharon and Susan, who were separated as children by their divorced parents. They accidentally meet at summer camp, and hatch a plot to get their parents Mitch and Maggie back together. There's a rival for Mitch's affections, Vicky but the girls soon scare her off.
It's a measure of the movie's success that there were three sequels filmed, and Parent Trap won two Oscar nominations.