On a sticky summer night in upstate New York, Anne and Marco Conti and Cynthia and Graham Stillwell, neighbors whose homes share a wall, celebrate Graham’s 40th birthday. It is the first night out for Anne and Marco since the birth of their daughter, Cora, six months ago. The babysitter canceled at the last minute, but they did not want to bring Cora along, as Cynthia does not like babies. Marco argues strongly that the new parents need a night out. The adjustment to the baby has been difficult. Anne, a stay-at-home mom who hopes soon to return to her job at a local art gallery, has postpartum depression. She struggles to breast feed or bond with Cora, who is fussy and refuses to sleep. Meanwhile, Marco struggles to keep his fledgling software development business afloat. Only Anne’s wealthy parents have kept Marco from filing for bankruptcy. They provided multiple generous loans despite their misgivings over Marco. The new parents leave their infant daughter home alone, bringing a baby monitor to the party.

At the dinner party, the alcohol flows. Anne, ashamed over not losing her pregnancy weight, watches as the flirtatious Cynthia makes eyes at Marco and draws attention to her generous bosom.