"Four seasons in, it is still laugh-out-loud funny. Every episode, every week," says USA Today's Robert Bianco about the hit series The Big Bang Theory. Subject his conclusion to empirical analysis by watching all 24 episodes of season four on 3 discs. This season, the Big Bang gang's romantic universe expands. On the rebound from Penny, Leonard falls for Raj's sister Priya. Sheldon gets a girlfriend - Amy, a dour neurobiologist who declares herself Penny's BFF. Howard and Bernadette heat up; meanwhile, Raj is romancing her in Bollywood daydreams. Observe all the of attraction in this genius, award-winning comedy.