A baby is left in a bassinet on the Stages' porch with a note written by the mother claiming that Rick is the child's father. While Rick tries to find the woman, Molly is stuck caring for the infant and the twins compete with the new arrival for their parents' attention.

Molly visits the home of an eccentric soccer teammate and meets the girl's bizarre parents, whose unusual behavior rivals that of her own folks. Meanwhile, Grant inadvertently agrees to do a school paper on Jerry's life, which hasn't been too exciting.

Molly's new lab partner in science class is Nick's current girlfriend, with whom Molly soon bonds after Nick dumps the popular girl. Meanwhile, Jerry arranges to take Mary to a swing-club outing to celebrate their anniversary, not realizing that it's not a dance group but rather a spouse-swapping coterie.