Our Idiot Brother is a story of three sisters and their one brother, whom they consider to be an idiot, because he is an idealist and an honest person.
Due to his dealing in Cannabis, Ned, is sent to Jail. When he comes back, he has no one, but his sisters to seek help from. His girlfriend has dumped him, kicking him out of the farm he used to work at. His sisters are all but living a trouble-free life: Miranda is an ambitious woman, who is into the profession of journalism, and is soon to get the biggest break in her life; Natalie is a lesbian and a huge liar, a behavior that puts her relationship with Cindy (Natalie’s girlfriend) at risk; and then there’s Liz, for whom being a good mother – rather unintentionally – becomes more important than trying to see that her marriage is falling apart. When the sisters realize the problem their brother is in, they agree to keep him with them in turn.
As the Idiot Brother moves in, the lives of Natalie, Miranda and Liz begin to get disrupted…in turn. While the things begin to become messy because of Ned, the sisters realize that their brother – when it comes to knowing people -may not be all too stupid.