You needn't be a member of Mensa get big laughs out of this release featuring all 22 episodes of the hit sitcom The Big Bang Theory. The second season begins with Leonard (Johnny Galecki) and Penny (Kaley Cuoco) returning from their first date, but things don't work out exactly as planned. Meanwhile, despite becoming even more obsessive and neurotic, Sheldon (Jim Parsons) strikes up an unusual friendship with Penny. Sara Gilbert has a recurring character arc as a fellow scientist who's interested in Leonard; and memorable guest cameos include Charlie Sheen, Summer Glau and George Smoot. Simon Helberg and Kunal Nayyar also star.