Joel (Jason Bateman) owns an extract factory, is trapped in a loveless marriage to Suzie (Kristen Wiig), and spends time with friend Dean (Ben Affleck), who is usually on drugs.
One day, an accident at the factory leads to a worker named Step losing his testicle. Cindy (Mila Kunis), a grifter, reads about this in the paper and promptly gets a job at the factory, flirting with Joel in order to pry information about Step.
In between committing petty thefts at the factory, Cindy meets with and convinces Step to sue the company.
Meanwhile, Joel mistakes Cindy's flirting for genuine interest and, while high, plots a scheme to sleep with her guilt free - deciding to hire a gigolo to seduce his wife. This would give him an opportunity to cheat on her. Upon sobering up, Joel goes to prevent it - but Suzie and the gigolo are already together.
Later, Joel meets with Step's lawyer, confusing the workers - who think he's planning on selling the factory. The workers begin to strike.
With the pressure mounting, Joel is forced to solve the strike, his marital problems and find out Cindy's true identity before things escalate further.