Dumb is a crime drama about a stoned and frustrated 30-year old actress who is stuck with the body and appearance of a teenager and hates it. She sees herself as dumb, leading a mundane life, without friends or dreams. All she has is her boyfriend, who later dumps her and gets arrested for dealing drugs. Determined to save him, she joins the police as an undercover agent posing as a high-school senior class student.
Blinded by love and power, she soon crosses the line becoming the new target of investigation. In way over her head, playing the role of her life, she realizes for the first time that she is not, in fact, dumb.