Psychiatrist Sidney Freedman composes a letter to Sigmund Freud during a visit to the 4077, while the rest of the camp endures the hijinks of a mystery prankster.

With British and American casualties heavy, the 4077th's supply of penicillin has been stolen. Father Mulcahy discovers, from Corporal Bryant, the location of some penicillin, and he and Klinger go out in search of it. They are shot at, but safely return with the drug and save the day.