Penny and Bernadette travel to San Diego to promote a new drug. Penny, thriving in her role as a sales lead, catches the attention of Danny, a representative from a rival company that Bernadette despises.

Back at home, Howard is left alone with the kids and invites the guys over for company. The day takes a turn when Sheldon finds a book on developmental experiments for children.

Leonard realizes his mother, Beverly, performed similar experiments on him throughout his childhood. When he calls her to complain, she reveals that the "experiment" on him never actually ended.

Danny offers Penny a job, leading her to realize she doesn't always feel appreciated by Bernadette.