Synopsis: Mamie Johnson looks the batter in the eye. Sizes him up for a curve- or a fastball. Stretches her 5'2" frame. And pops a surefire, windup, coming-right-at-ya pitch smack dab over the plate. One that lets the batter know that this "peanut of a girl" means business. Fueled by her passion for the game and buoyed by the inspiration of Jackie Robinson, Mamie Johnson is determined to be a professional baseball pitcher. From the time she insists on…