Hardy Boys CASEFILE Number 2 cover. Title: "Carbonation Conundrum". Author: Franklin W. Dixon. Cover illustration shows two young men, Joe with blonde hair in a red shirt and blue pants, and Frank with dark hair in a light blue shirt and yellow pants, at the park. Joe is on the left, Frank is on the right. Both have happy expressions. Joe holds a can of Coke. Frank holds a can of Pepsi. Tagline: "Coke, Pepsi, or Danger?" Cover has a worn, vintage look.