Greg and Amanda are happy. They've been together thirteen years and have two young daughters. They're still in love. Dan and Sarah aren't so fortunate. Their marriage has grown stale. They're going through the motions for the sake of their 15-year-old son. Friends and colleagues, Greg and Dan attend a conference where a chance encounter with two fellow delegates, Lynda and Liz, leads to a drink in the hotel bar, followed by another, and ultimately one too many. The men have an opportunity to cheat. Dan's not interested. He's too upright. Uptight too. But Greg, at the age of 39 and conscious that he might never have this opportunity again, is tempted. After all, where's the harm? Amanda will never find out.