David Theune

Raj is concerned that his scientific peers will no longer take him seriously after publishing a paper that suggests he may have found alien life. Meanwhile, Leonard hopes to become the principal investigator on a plasma physics study.

Sheldon is determined to get his own back, when Wolowitz dresses up as him for Halloween. Leonard is upset when Penny can't recall their first kiss.

Glenn announces that all employees will receive a bonus if the store reaches a sales goal by the end of the day. Jonah has an encounter with Amy's husband.

No longer feeling academically challenged at his high school, Sheldon decides to audit Dr John Sturgis' college class.

Viv gets a reluctant Katie to help out with the school Christmas pageant; Greg takes Taylor and Oliver to a nursing home to cheer up the residents.

Bonnie worries about Adam when his amends to a woman from his past doesn't go as planned; Tammy pays a visit to the steakhouse she once robbed.