Penny hosts a Hallowe'en party, putting Leonard, Sheldon, Wolowitz, and Koothrappali through a new test of their social skills.
Charlie and Alan go on a double date, leaving Jake home alone for the first time.
Charlie loses a woman to the young, handsome handyman (guest star Enrique Iglesias) working at his house.
While Alan and Jake are away on a road trip, Charlie is visited by the ghosts of his ex-girlfriends.
When Nicolas (recurring guest star GILLES MARINI) invites Caroline to a dinner date at his loft, she asks Max and Deke (recurring guest star ERIC ANDRÉ) to join her to help make sure she doesn’t do anything she might regret. Also, Max and Caroline treat themselves to very special hair appointments.