A budding novelist and her film director husband, Kelly (Melanie Lynskey) and Jeff (Joe Swanberg) and their two-year-old son live a peaceful existence in Chicago. But when Jeff's irresponsible younger sister, Jenny (Anna Kendrick), comes to live with them after a breakup, things start to change. Jenny begins a rocky relationship with a baby sitter-cum-pot dealer (Mark Webber), and she and a friend, Carson (Lena Dunham), instigate an evolution in Kelly's life, as her career and her relationship with her husband begin to grow in new directions. But are they welcome ones?