Margaret Tate (SANDRA BULLOCK) is such a feared editor-in-chief at a NYC publishing firm that most of her staff takes cover or runs the other way whenever she passes by. That is, except for Andrew Paxton (RYAN REYNOLDS), her personal assistant for the past three years who takes her abuse in hopes of getting his own work published.
But things change after she fires Bob Spaulding (AASIF MANDVI) for failing to do his job up to her standards. And that's because her visa has expired and she's to be deported back to Canada where she won't be able to return for a year or telework for an American company.
Desperate for a quick solution, she suddenly announces to her bosses that she and Andrew are engaged, much to the latter's surprise, although he plays along with the unexpected ruse. That includes going down to the local immigration office where they encounter Mr. Gilbertson (DENIS O'HARE), a marriage fraud investigator who's suspicious of their reported engagement.
With just a weekend to prepare for an examination by Mr. Gilbertson that he thinks will expose their fraud -- and thus result in Margaret's deportation and Andrew's imprisonment -- the "couple" head to Sitka, Alaska to celebrate the 90th birthday of his Grandma Annie (BETTY WHITE).
Having heard horror stories about Margaret, she and Andrew's parents, Grace (MARY STEENBURGEN) and Joe (CRAIG T. NELSON), are surprised he's brought his boss along for the party, and are then floored -- as is Andrew's ex-girlfriend, Gertrude (MALIN AKERMAN) -- upon learning of the engagement.
While Grace and Annie quickly warm to the idea, including taking Margaret to their version of a bachelorette party with the small town's lone exotic dancer, Ramone (OSCAR NUŅEZ), Joe is suspicious, no doubt fueled by the father and son not seeing eye to eye for some time now. From that point on, and despite not really liking each other, Margaret and Andrew then begin to have a change of heart as they continue their ruse as an engaged couple.