The son of a depressed but doting mother (Hope Davis) and a father who is serving time for tax evasion, wealthy teenager Charlie Bartlett (Anton Yelchin) — after being expelled from several private academies for various infractions — enrolls in a public school run by embittered alcoholic Principal Nathan Gardner (Robert Downey Jr.), who was formerly a history teacher. Unable to fit in with most of his fellow students, Charlie is diagnosed with ADHD. He forms an alliance with school bully Murphy Bivens (Tyler Hilton) and offers him half the proceeds from the sale of a variety of prescription drugs Charlie obtains by feigning physical and emotional symptoms during sessions with different psychiatrists.