In Chicago, Clay is a 35-year-old minor league hockey player and his wife Olive is a doctor. The movie begins as they explain they can no longer be together to their son Wesley.Wesley is a dog.The process of dividing up the couple's possessions must take place. Clay will move into his RV, which will be parked by a lake outside the city.Clay has everything he needs and starts to leave, but as he calls to Wesley to go with him, Olive demands to know why. She has just assumed she would get to keep the dog. However, Clay adopted Wesley before he and Olive were together. He no longer has the papers to prove this. The process of determining who gets the dog has to begin.Clay's best friend Rhett is a coach of a hockey team of young boys, including his 9-year-old nephew Koji, who is having problems at home, meaning Rhett has a lot of added responsibility taking care of the boy.Olive's best friend is Libby, a nurse.The couple and their friends take Wesley to a park. Clay goes to one side and Olive to the other, and then Wesley is released to decide who he will go with. Wesley goes back and forth and then runs away. He is found by Glenn, a dog expert who recommends the couple take advantage of his services. He shows how well-behaved the dogs he is walking are and says Wesley can get the same training. Hearing that Clay and Olive are no longer together, Glenn indicates a possible romantic interest in Olive.At first the couple tries to stay together, but that won't work.The couple go before Judge Hutcheon to decide who will get the dog. There is no clear winner and no evidence Clay adopted Wesley. Clay claims Olive can't take care of the dog while she is at work, though it is never explained how Clay never has to work when Olive does, or if this is the case, or what happens to Wesley in that situation. Olive clearly will have the better place to live. So Wesley will get treated like a child in the same situation: Stay with Olive most of the time, with visitation for Clay. Dr. Wendy, a behavioral veterinarian, will evaluate Wesley and both living situations. Already, Dr. Wendy says, Wesley shows signs of stress which must be resolved.The couple take Wesley to one of Glenn's classes. Glenn continues to show a romantic interest in Olive.Things don't go well when Olive has to leave Wesley alone. She comes home to find the apartment wrecked.Meanwhile, Clay is helping Rhett with Koji, who isn't playing very well. They go to the locker room (or that's what it would be called, but there no actual lockers) and gives an inspirational speech to the boy , and helps the boy to be more aggressive. Koji later repeats the same advice to Clay when he needs it.Olive takes Wesley to doggie day care, but that turns out to be a disaster and both "parents" get called when Wesley wrecks the place.Olive and Glenn go out on a date, and it goes pretty well, but Olive is not really ready to commit. At the same time, when she and Clay interact, there are signs Clay and Olive might be willing to reconcile.The time arrives for both homes to be evaluated. Dr. Wendy's visit to Olive does not go all that well, but she would be the clear winner after what happens when Dr. Wendy goes to see Clay, who diligently prepares his place for the visit. During the night Wesley makes a mess of the RV and Clay has no time to clean up. Furthermore, as he makes a vain attempt to do so, Dr. Wendy arrives as he is locked out in his long underwear. There is no point in continuing this disastrous visit, and Dr. Wendy never even sees what the inside is like.Olive is determined to attend a winter festival with Wesley, and she helps Glenn pass out flyers for his business. Clay shows up dressed as Wesley's favorite toy Bob Bumblebee and persuades the band to let him sing. Glenn objects when Olive is distracted from what she came to do, and eventually he and Clay get in a fight.Wesley gets lost and is found by a group of homeless people. Olive and Clay work together to find the dog and discover a man stealing the flyers they put up, and follows the man to a building where the group claims the dog is theirs and won't give him up.The judge's decision is predictable. Except for one thing. Somehow she has found the records that indicate Clay did adopt Wesley on his own. So despite everything, Clay gets the dog and Olive's tearful protests do not help.There is an additional complication, one that means Olive will get to spend more time with Wesley after all, and she will have to find a way to take care of the dog when she is at work. After a key player is injured Clay is called up to the major league Chicago Wolves. That means lots of travel.When Clay gets hurt Olive comes to see him and it looks like they will get back together. In fact, they do, and the movie's final scene shows the couple and Wesley in a nicer home with a baby.