The population explosion occurs when widowed Navy nurse Helen North (Ball) meets handsome Naval officer and widower Frank Beardsley (Fonda). They have much in common, too much in fact, she has eight kids and he has ten and when they tie the knot, anarchy reigns in the Beardsley-North merger. The opposing camps of step-siblings do all they can to sabotage each other and their parents' union. But, through it all, mother lovingly cares for her "troops," while father patiently coaches his coming-of-age kids in more delicate matters, and resentment soon gives way to respect and something bigger than anyone could have imagined!