Sophie and Andrew are looking for relief from the daily grind - if not each other - so when a friend puts them in touch with William and Beth, newlyweds looking to swap houses for the summer, it sounds like a great idea. They find themselves in a stylish Connecticut home, while William and Beth take over their lived-in family house in London. The weeks away work an unexpected magic for Sophie, who begins to find a sense of happiness, but Beth has no such luck and grows increasingly miserable. The two marriages - one crushed by the weight of years, one shiny and new - slide into reverse. And what was meant to be a great summer adventure begins to have dramatic consequences none of them could have foreseen. . . and all are powerless to stop.