A married couple travels from Chicago to spend Christmas with the wife's family in a small town in Ireland, for a holiday that will test their patience--and their marriage.
In Chicago, Jack and Caroline are not married but they host a Christmas party together. One couple attends with their young child Henry because they can't get a baby sitter. This leads the couple to discuss whether they want children. Jack enjoyed having Henry at the party and wants children, but Caroline is a marketing executive at an unidentified Fortune 500 company and has a chance to advance further. A child would interfere with this, and Caroline grew up in a noisy family and isn't interested in any more of that.
Jack and Caroline fly to Ireland and drive to the town where Caroline's family still lives. Justin thinks he can drive until he forgets and rives on the wrong side of the road, and then he turns the car over to Caroline. When they arrive in town, there is a live nativity scene where Mary is actually named Mary.
Caroline's father Calum runs the pub Reilly's, which has been in the family for 100 years. Things are quiet but a Christmas Eve celebration there is a tradition, so it is hoped things will improve.
At Caroline's family home, mother Nadine is so happy to see her daughter. So are sisters Maeve and Pauline. Mave has baby Clara, and Pauline is chasing noisy boys Sean and Patrick.
Caroline goes back to the pub and learns it may soon close. Her ex Cormac runs a popular new pub with karaoke. She comes back home to find Jack playing with Sean and Patrick. Patrick ties up Sean and when Jack rescues him, Patrick hits him in the genitals.
Then Jack is hit by a soccer ball. He figures out the ball came from a nearby soccer field and brings the ball back. Caroline's brother Malcolm is annoyed to hear Jack call the game soccer. However, as Jack learns when he sits down with Malcolm's daughter Saoirse, the game is actually Gaelic football, where players can use their hands briefly. Saoirse would like to play, but the men don't think she would be good enough. They are getting ready for a competition with Cormac's, and the pub represented by the loser of the game has to close. Among those playing on the team are Aiden, who is proud to learn what his son Patrick did to Jack, and Finn, Clara's father. Malcolm's 12-year-old son Liam is also playing but he is not very good.
When Jack and Caroline go to bed, they are warned their sofa bed is very noisy. Although they are not doing anything immoral, they make so much noise the family think they are. And the whole family gathers in their room the next morning.
Maeve and Pauline would like a break from their children, but there's no one to take care of the kids. Nadine is too busy, as she has been all her life. Jack volunteers to take care of the kids, because he enjoys spending time with them. Caroline is not so sure, and reminds him if he really wants kids, they are a responsibility and he can't just hand the kids off to someone else.
Caroline and her sisters go to Cormac's and have fun. Cormac is happy to see his ex and wonders if she is with anyone. Caroline exaggerates her situation while her sisters sing. Everyone drinks, of course.
Jack sees Liam in a tree and wonders what he is doing up there. The kids have gone on ahead. Liam confesses he'd like to hurt himself so he won't have to play. Jack says if he doesn't want to play, just tell his father. Then Jack catches up with the younger kids, puts them on what are essentially leashes, and makes the mistake of letting them go in a candy store. While Clara needs changing, the boys take off without pants and Jack has to search for them.
While still at Cormac's, Caroline throws up and wonders if this could mean she is pregnant. She goes in a store hoping no one will see her buy a pregnancy test. A nosy neighbor who knows her sees this.
It is the Reilly family's turn to do the live nativity scene, but there are problems. When Jack catches up with the boys, Patrick is climbing up on a roof with Christmas decorations. Jack hands Sean his phone to give Sean something to do, and hangs Clara on a Santa Claus decoration. Though scared of heights, Jack goes up the ladder and Patrick taunts him as Jack tried to get him to come down. All this time, people down below are singing. Then someone discovers Clara has been abandoned. Jack finally gets Patrick to come down but now Clara is missing. The family is upset when Clara is delivered to them and Jack shows up with the boys and gets reprimanded for messing up. Jack has decided children are too difficult to handle.
Caroline takes the pregnancy test and it is positive but as she and Jack discuss their future, she can't admit what she knows.
The next morning Jack gets dragged out of bed by Malcolm and his in-laws, who are angry Liam won't play soccer. Jack is told he will take Liam's place on the team. Jack doesn't want to do it, because he is not athletic, but he will try.
Caroline and Nadine spend the morning together. Nadine knows the truth, and they talk. Nadine explains she knows about Aiden's bet which could lead to the pub closing, but that is inevitable because no one in the family will take over. Caroline says she could stay and do it, but Nadine won't let her do something she doesn't really want to do.
As the teams take the field in uniforms, Cormac comments on how Liam has grown but Jack says no, he is not Liam. Then as they play Jack proceeds to make a number of errors. The team is not doing well. Then Jack gets hurt. Can the team play a man down? Jack suggests Saoirse, who has said she wants to play. The men are reluctant but agree, and Jack and Saoirse switch clothes. Saoirse is a great player and she leads the team to a win.
At Reilly's, Calum tells the few men who are there to leave, thinking his team will lose the game, because he wasn't there. He puts out the Closed sign. But the family arrive at the pub cheering their win. There will be a celebration. However, the pub will still close.
But not everyone is happy. Caroline and Jack get separated and each tries to find the other. When they finally do, Jack has wrecked the car. Caroline tells Jack she is pregnant, but Jack thinks that is wonderful and he does want kids again. And Caroline wants to stay.