David Theune

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

While Raj is worried that people won’t take him seriously in his own field after publishing a paper suggesting he may have discovered alien life, Penny encourages Leonard to stand up for himself when he wants to be the principal investigator on a plasma physics study.

When a doctor becomes a patient, his co-workers rally around him, whether he likes it or not. Matt and Serena need to talk.

Alex tries to hold on to her peaceful vacation vibes. Joyce faces a design crisis in the birthing center. Matt and Serena reassess their working relationship.

Alex helps Joyce hire a midwife; Bruce joins Matt for an ambulance ride along.

After Bruce is attacked at the hospital, Matt helps him deal with the aftermath. Alex motivates Joyce to amp up security, while Ron and Serena debate who is more qualified to defend themselves.