Margaret Tate (played by Sandra Bullock) is the executive editor-in-chief of a publishing house in the United States. Her strict and efficient manner makes all her colleagues fear her, including Andrew Paxton (played by Ryan Reynolds), who has been hoping to become an editor but has never been recognized.
Margaret is so focused on her work that she neglects some legal issues. When she is suddenly informed that she will be deported back to her homeland, Canada, and may even lose her job, she has no choice but to "admit" that she is about to marry Andrew. Andrew reluctantly accepts Margaret's marriage scheme, but one of the conditions is that he will eventually become an editor.
As government officials begin investigating whether they are really a couple, they are forced to go to Andrew's hometown in Alaska over the weekend to prove that they really intend to get married. There, Margaret meets Andrew's hospitable yet quirky large family, including his warm and welcoming mother Grace (played by Mary Steenburgen), his domineering father Joe (played by Greg T. Nielsen), and Annie, the straightforward and mischievous 90-year-old matriarch (played by Betty White)... However, the family doesn't know their true relationship, so they have to hide it, which leads to quite a few jokes. Meanwhile, a chemical reaction slowly occurs between Margaret and Andrew as their relationship evolves. Margaret discovers that Andrew's family is actually very wealthy, and Andrew finds out during their interactions that she isn't as rigid as before. Although Margaret finally feels guilty and reveals the truth about their fake marriage at the wedding scene, Andrew still goes back to New York to bring her back and they end up getting truly married.