Walden thinks his girlfriend is cheating on him; Alan starts dating Larry’s sister, Gretchen (Kimberly Williams-Paisley).

After Leonard, Sheldon and Wolowitz celebrate the completion of the top secret air force project, they are met with an unpleasant surprise. Also, Amy is offered a summer position as…

Colonel Williams, an Air Force representative from the Department of Material Command sits down to talk with Wolowitz.

With Wolowitz AWOL with one of her friends, Penny’s recruited to fill in for him on the guys’ Halo team