A fellow comic book enthusiast's hitting on Penny leads to Leonard, Raj, and Howard going to a bar's Ladies' Night.

Leonard and Raj take Wolowitz to Las Vegas to help him get over his break-up with Leslie. Sheldon, home alone and looking forward to it, locks himself out and has only one other place to stay—Penny's.

Leonard is torn between being honest or self-serving when Stuart asks his advice for an upcoming second date with Penny. Wolowitz realizes there's a crucial error in a toilet he designed for the International Space Station.

Discovering that Leonard, Raj, and Howard fudged the results of his Arctic research expedition, a disgraced Sheldon heads home to Texas