“Look, Chief, if it’s a cipher, couldn’t you read it? There are nine words in the message, and I’ve always understood any cipher can be solved if there’s a long enough message.”
Mason said, “I guess that’s right, but I don’t think it’s an ordinary cipher in which letters are transposed.”
“Why not?”
“Let’s analyze this. There are nine words. Five of them begin with the letter c. The letter c is in every single word at least once.”
“Wouldn’t that indicate it was either e or a?”
“I’m afraid you’re missing the most significant thing about the whole message, Della.”
She studied the typewritten copy of the message which Mason pushed across to her. After an interval of silence, she said, “I’m afraid I don’t get it.”
“Look again. It’s relatively simple.”
“You mean that there are no short words in it?”
“That’s one thing,” Mason said. “The shortest word in there has five letters. The longest has six. That’s an interesting peculiarity of the message. Nine words. Three of them have five letters, and the other six have six letters. But there’s something that’s far more significant than that.”
“What?”
“Give up?” he asked banteringly.
She nodded.
“The last fourteen letters of the alphabet aren’t represented there at all,” he said. “The entire message is composed of words made up from the first twelve letters of the alphabet.”
Della Street frowned, stared down at the typewriting, then said thoughtfully, “That’s right. What does it mean?”
Mason said, “I’ll tell you one other significant thing. Every word contains either the letter a or the letter b.”
“I don’t see that that’s as important as the frequency with which the letter c occurs.”
“Perhaps not, unless we also consider positions. Every word has either a or b in it, but neither a nor b appears at the first of the word or at the ending. They’re always either the second or third letter from the end of the word.”
There followed an interval while she checked his conclusions, then nodded again.
Mason said, “That empty can is significant in a good many ways. I’m wondering whether Tragg has overlooked some of those things, or is just sitting tight and awaiting developments.”
“What, for instance?” Della asked.
“That can conveyed a message to some person,” Mason said. “That means two persons were concerned in the crime. That, in turn, means that the someone who put the can there must have had easy access to the basement. It also means that the person for whom the message was intended must have had easy access to the basement. Yet it also means that those two persons didn’t have access to each other.”
“I don’t get you,” Della Street said.
“It’s simple,” Mason pointed out. “If the two persons could have met and talked with each other, there would have been no necessity for going to all that elaborate trouble of scratching a message in the top of the can, sealing the can, and placing it in the cellar.”
“Yes. That’s true.”
“The fact that the cellar was chosen as the place where the message was to be left means that both parties must have had access to the cellar.”
She nodded.
“Therefore,” Mason said, “we have a peculiar situation. Two persons have access to the same place, yet those persons don’t have contact with each other, and that place is highly unusual — the cellar of a big, rambling, frame residence.”
Della Street said excitedly, “Now that you analyze it, it’s plain as day. One of the persons had to have access to the cellar through the garage that Hocksley rented, and the other one because he lived in Gentrie’s house.”
Mason said, “That’s one of the possibilities.”
“But, Chief,” Della Street said, “that brings up all sorts of complications.”
“That’s just the point.”
“Then you think Junior is mixed up with it — and Opal?”
Mason said, “The evidence seems to point the other way.”
“What do you mean?”
He said, “Then the message in the can becomes perfectly meaningless... so far as the murder is concerned.”
“Why? Oh, I get it. Because he and she were together. Is that right?”
“That’s right.”
Della Street said with a smile, “Once that message is deciphered, it may turn out to be ‘I love you, darling, no matter what happens.’ Persons in love are inclined to do things like that, you know — or do you?”
Mason nodded, said, “Frankly, Della, if it had been a simple cipher where letters had been transposed in order to make a message, I would have been very much surprised if it had had anything to do with the murder. But as it is, I’m inclined to attach more importance to it. But the perfectly obvious and logical point seems to have escaped everyone.”
“What’s that?”
“The one real clue as to the identity of the person for whom the message was intended.”
“What’s the clue?”
Mason said, “The fact that only one person got it, of course.”
“You mean...?”
“Arthur Gentrie.”
“Junior? I thought you said he...”
“No, the father. He’s the one who went down in the cellar. He says he found the can lying in the box and opened it in order to mix up paint in it. Then he threw the top away, but you notice that when Steele became interested in the top, Gentrie saw that the tops were substituted. The one with the code message on it remained in the box, and one that had no message was put on the workbench.”
Della Street said, “My gosh, Chief, it’s perfectly obvious, now that you mention it. The way you sum it up, it sounds rather damning.”
Mason pulled the sheet of typewritten paper over to him, started studying it. Abruptly, he laughed.
“What is it?” she asked.
“That code,” he said. “It’s absolutely simple.”
“You mean you can read the message?” Della Street asked.
Mason nodded. “It’s absurdly simple when you approach the problem from the right angle.”
“What’s the right angle?”
“Notice,” Mason said, “that only the first twelve letters in the alphabet are employed. Notice that every word contains either a or b, and that a or b, whenever it appears, is either the second or the third letter from the end of the word. That, coupled with the fact that the words have either five or six letters, is absolutely determinative of the whole business. I wonder if Tragg has got it by this time.”
Della Street said, “I don’t get it.”
“Twelve letters,” Mason said. “Good Lord, Della, it fairly hits you in the face.”
“It doesn’t hit me in the face,” Della Street laughed. “It doesn’t hit me anywhere. I miss it altogether.”
Mason pushed back his chair. “I’m going out for fifteen or twenty minutes, Della. Think it over while I’m gone.”
She said, “Ordinarily, I’m a peaceful woman. I’m not given to homicidal mania, but if you arouse my curiosity this way and then try to go out of that door without telling me what the message says, I’m very apt to assault you with a deadly weapon before you get as far as the elevator.”
Mason said, “I don’t know what the message says.”
“I thought you said you did.”
“No. I said the solution was simple. Good Lord, Della, I can’t give you any more clues than that. I’ve virtually told you the whole thing now.”