High school sweethearts Frank Beardsley (a widowed Coast Guard Admiral) and Helen White (a widowed handbag designer), are reunited when Frank and his family move back to his hometown of New London, Connecticut. After unexpectedly encountering each other at a restaurant while on separate dates, the pair run into each other again at their 30-year class reunion.
Instantly rekindling their old sparks, the two quickly decide to marry in a private ceremony. They are quite aware of the fact that Frank already has eight children from his first marriage, and Helen has ten from her first marriage. The family moves into a new home, on the same property as the lighthouse where Frank and Helen shared their first kiss, joined by the North children's numerous pets and Frank's housekeeper, Mrs. Munion.
It soon becomes apparent that, as a Coast Guard Admiral, Frank has a very regimented view of how things should be done, whereas Helen is an artist (a designer by trade) with a more free-spirited, lackadaisical attitude. Their respective children, who are a product of their parents' views, are shocked by the news of their parents' quickie wedding and don't get along well at first, even turning a planned lighthouse renovation project into an all-out paint fight.
Frank's oldest son William calls a meeting among the kids and explains that they can better rid themselves of their new situation by joining forces to make their parents' respective philosophical differences apparent, and effectively cause them to start fighting. During this time, the kids gradually begin to bond, taking part in such activities as attending their siblings' soccer games and helping William in his campaign for class president.
A short time later, Frank and Helen attend a formal Coast Guard dinner where Frank's superior, Commandant Sherman, officially offers Frank the opportunity to be his successor. Frank respectfully declines the offer, citing both his obligation to the Coast Guard Academy and his new family. Meanwhile, the older kids throw an all-out party that quickly grows out of control, and when the couple returns home to find their place in total chaos, Frank is furious, while Helen takes a more laid-back approach, which only angers Frank further and causes their worst fight yet. Realizing just how happy their parents have been together, the kids begin to sense that maybe they pushed things too far.
The next day, Frank informs Helen that he has decided to take the position as Commandant after all, and the pair schedule a family meeting to inform the kids of this new development. As they return from school, jubilant over having defended their younger siblings from bullies and with the news of William having won the class election, Frank quickly deflates the mood by telling the kids of his decision to accept the new position. Feeling guilty for having torn their parents apart, the kids set about undoing their mistakes, even enlisting Helen to aid in their efforts. Together, the older kids launch the family's boat in an effort to catch Frank, but he is convinced that Helen no longer wants to be with him, until he sees her turn on the lighthouse spotlight (a reference to a story Frank had told Helen about a beautiful female light-housekeeper). Successfully reunited, the pair tie the knot once again, but this time with the rest of the family involved.
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