Adam and Rachel wage a territorial battle over whose place to move into; David and Karen hire a nanny and differ over the issue of having another baby; as Pete and Jenny anxiously await the birth of their first child, Pete's meticulous planning comes to pieces when he mislays his mobile phone.
After moving in with Rachel, Adam learns that she is still married; Karen agrees to have another child with David, but then finds out he's made a bad investment; Pete and Jenny have difficulties with their newborn baby.
David seeks sexual advice from Adam, saying that Karen just doesn't arouse him anymore; Pete seeks to resume intimacy with Jenny now that their baby has been born.
A meeting with a famous and handsome author, who wants her to edit his new novel, tempts Karen with thoughts of adultery; Adam is inspired to resurrect an old novel he was writing; and Pete's controlling parents make a visit.
Tired of Adam's preoccupation with a glamorous female neighbor, Rachel decides to baby-sit for Pete and Jenny, who need to get out so that they have something to talk about besides the baby. Meanwhile, David and Karen decide to see a marriage counselor.
David and Karen invite the other couples to a black tie charity dinner where David spends the evening networking, but Jenny gets drunk and starts a fistfight with his female boss. Meanwhile, Rachel reveals a secret to Karen.