"This," said Roberts. He reached into the inside pocket of his sport jacket and withdrew a business-size envelope, which he handed over to Stevenson. It was another crank letter, in the same newspaper clipping form as the first two. It read: Dear Mr. Editor, The bad boys were captured. They could not escape the Scorpion. I left the mark of the Scorpion on their jackets. Criminals fear the mark of the Scorpion. They cannot escape. This is my third letter to you. You should warn all criminals to leave the city. They cannot escape the Scorpion. WARN YOUR READERS. Sincerely yours, THE SCORPION Stevenson read the letter. "Well, well," he said. "He says that's the third letter," Roberts pointed out. "We asked around in the office, and we found out who got the first two. They were both back a ways. The first one was early in the summer, and the guy who read it remembered it said something about a bank robbery. So I was sent out this morning to check up on bank robberies in June and July. You're the third one I've talked to this morning. The first two figured me for some kind of nut." * * * * * "My Captain figures me the same way," Stevenson told him. "What about the second letter? Or, wait, don't tell me, I'll tell you. It's that guy in August, the one who ran amok over in Canarsie." "Right you are," said Roberts. "How did you know?" "I was there. He left his mark on the rifle stock." "Okay," said Roberts. "So there's something in it, after all." "There's _something_ in it," said Stevenson. "The question is, what?" "Well," said Roberts, "what have we got so far? Somebody--call it person or persons unknown, for the fun of it--is stepping in every once in a while when there's a crime being committed. He stops it. He calls himself the Scorpion, and he uses some pretty dizzy methods. He melts automobile tires, makes a rifle too hot to hold, makes knives and leather jackets ice cold--how in heck does he do things like that?" "Yeah," said Stevenson. "And just incidentally, who is he?" "Well," said Roberts, "he's a kid, that much is obvious. That whole letter _sounds_ like a kid. Talking about 'the bad boys' and stuff like that." "What do you figure, some scientist's kid maybe?" "Maybe," said Roberts. "His old man is working on something in his little old laboratory in the cellar, and every once in a while the kid sneaks in and makes off with the ray gun or whatever it is." Roberts laughed. "I feel silly even talking about it," he said. "I'd feel silly, too," Stevenson told him, "if I hadn't seen what this kid can do." "Can we work anything out from the timing?" Roberts asked him. "He seems to show up once every couple of months." "Let me check."