To discover who would be most qualified to be best man and maid of honor at their wedding, Sheldon and Amy subject their friends to a series of secret experiments. Also, Penny reveals her true feelings about Amy.

Koothrappali finds himself in the middle of domestic drama when he learns the woman he's dating, Nell, has a very upset husband, Oliver. Also, when Sheldon rents his old room back for a quiet place to work, he drives Leonard crazy by being a model tenant.