When Sheldon won't tell anyone why he's never mentioned Tam, his childhood best friend, Leonard takes matters into his own hands. Also, Bernadette and Penny take out Raj's fiancée, Anu, for dinner to get the skinny on her.

When Wolowitz dresses up as Sheldon for Halloween, Sheldon seeks retaliation at Leonard and Penny's Halloween party. Also, Leonard is shocked that Penny doesn't remember their first kiss.