The fourth season of The Big Bang Theory finds Leonard (Johnny Galecki) falling for Raj's sister Priya following his break-up with Penny (Kaley Cuoco). Meanwhile, Sheldon (Simon Helberg) finds romance with a neurologist who quickly establishes herself as Penny's new best friend. As Howard and Bernadette's relationship blossoms, Bernadette finds herself plagued by Bollywood daydreams starring Raj (Kunal Nayyar).

This release includes all 23 episodes of the brainy sitcom The Big Bang Theory, following the romantic and practical misadventures of two genius physicists, who are at the top of their fields in science, but at the bottom of the totem in playing the field. The two continually attempt to bring their social skills into par with their laboratory skills, and living across the hall from a charming blonde actress gives them plenty of motivation.