UNITED INTERNATIONAL SPACE AGENCY

In Wabasha, Minnesota, retirees John Gustafson and Max Goldman are feuding next-door neighbors. Living alone, they spend their time ice fishing, trading insults, and pulling cruel practical jokes on each other, including John leaving a dead fish in Max's truck.
Their rivalry irritates their friend Chuck, owner of the town bait shop, and Max's son Jacob, who is running for mayor. Dodging the attempts of IRS Agent Elliot Snyder to collect a serious debt, John supports his daughter Melanie when she separates from her husband Mike, whom John dislikes.
John and Max both find themselves attracted to Ariel Truax, a free-spirited English professor who moves in across the street. Chuck has Thanksgiving dinner with Ariel, prompting John and Max to compete for her affections. Chuck dies, and Max discovers John's IRS debt. John spends time with Ariel, revealing that he and Max used to be childhood friends.
John and Ariel have sex – his first time since 1978 – and a jealous Max drives John's fishing shanty onto thin ice, which John narrowly escapes. He confronts Max, and the source of their animosity is revealed: Max resents John for marrying Max's high school sweetheart. John explains she was unfaithful and Max was happier with the woman he did marry, but Max reminds John that he will have nothing to offer Ariel once the IRS takes his house.
With this on his mind, John ends his relationship with Ariel. Ariel then gives John advice, warning him that he will regret the risks he did not take in life.
Jacob is elected mayor, and Max continues courting Ariel. On Christmas, Melanie comes to visit and John is upset to learn she has reconciled with Mike. Giving Melanie the same warning Ariel gave him, he warns that she will regret the risks she did not take in life, and then John leaves for the local bar. At Melanie's request, Jacob asks Max to settle things with John, but the fathers are unable to mend their dispute and John storms out of the bar. Max soon follows and finds John in the snow, having suffered a heart attack. At the hospital, Max checks in by declaring he is John's friend. He tells Ariel what happened, and she reconciles with John as he recovers.
Max tries to resolve John's debt, but the unsympathetic Agent Snyder prepares to sell John's house and possessions. Barricading the house, Max leaves a fish in Snyder's car and buries him in snow, while Jacob manages to temporarily block the property's seizure. Spring arrives, and John and Ariel get married. As a wedding gift, Max informs John that he and Jacob have paid off the debt. The newlyweds drive off, but not before John finds Max has left a fish in the wedding limo car. Max leaves to find a date of his own, as Jacob and an officially divorced Melanie begin a new romance with each other.