Florence Marr (Greta Gerwig), an aspiring singer, is struggling to find her place in the world. She works as a personal assistant to the Greenberg family, beginning and ending each day tending to other people's needs. In sharp contrast to the Greenbergs' bustling life in their elegant Hollywood Hills home, Florence lives alone in a tiny studio apartment and sings at open-mike nights.

When Phillip Greenberg (Chris Messina) takes his wife and children on an extended trip abroad, Florence is suddenly left more to her own devices. She makes the occasional visit to their home to check up on the family's dog Mahler, and look in on Phillip's brother Roger (Ben Stiller), who has come to L.A. to housesit.

Single and fortyish, Greenberg is intelligent, witty, sharp-tongued - and, like Florence, something of a lost soul; he is at a crossroads in his life. He has been working as a carpenter in New York after an early career as a musician in L.A. petered out. Greenberg claims to be "doing nothing" and his most tangible projects include drafting letters of complaint and building a doghouse for Mahler. Roger tries to reconnect with friend and former bandmate Ivan (Rhys Ifans) and old flame Beth (Jennifer Jason Leigh), but they've moved on with their lives while Greenberg has been stuck treading water. In trying to restart his life, Greenberg finds that times have changed and old friends aren't necessarily still best friends.

After years of living in New York City, Greenberg doesn't drive and finds himself stranded at his brother's house. His vulnerability immediately endears him to Florence, who helps him navigate Los Angeles and take care of Mahler. What begins as a courtesy to her employer develops into a charmingly eccentric and unexpectedly significant connection. As Greenberg discovers there is only so much "nothing" you can do, the awkward beauty of what he builds with Florence starts to look more and more like a reason to be happy.