1. "The Fortification Implementation"
When Sheldon and Amy build a blanket fort, they come to major crossroads in their relationship. Also, Wolowitz meets the half-brother he never knew he had, and when Penny is invited to appear on Wil Wheaton's podcast, she and Leonard have a huge, on-air argument, on THE BIG BANG THEORY, Thursday, April 9 (8:00-8:31 PM, ET/PT), on the CBS Television Network. Pictured left to right: Jim Parsons, Johnny Galecki, Simon Helberg and Kunal Nayyar Photo: Sonja Flemming/CBS ©2015 CBS Broadcasting, Inc. All Rights Reserved