Scott Gimple was the showrunner for five seasons of “The Walking Dead” before becoming chief content officer for the entire franchise. And in that time, the series has become a content universe, with a spinoff series, video games and both a movie and another spinoff in the works. Kai Ryssdal interviewed Gimple in his Burbank office, not too far from a life-sized statue of Han Solo frozen in carbonite. They talked horror what it’s like to direct the storyline for an entire franchise. And Gimple made a passionate pitch for Ryssdal to give the series a shot.