Beth (Julia Louis-Dreyfus), a popular writer, and her husband Don, a well-liked teacher, share the kind of relationship that truly, seriously, for the love of God cannot be real: that is, they're actually in love. Even after decades of marriage, parenting, and their own successful careers, their physical spark has somehow not diminished; in fact, they seem to relish the opportunity to share a single ice cream cone and drive others -- including their son, Charlie -- mad. Should it come as a surprise then that his own marriage is in crisis? But when Beth discovers that Don has been untruthful to her about his opinion of her work for years -- Beth's world comes crashing down. Has their whole relationship been one Big Fat Lie?