“There’s something we’ve overlooked,” Vance went on, disregarding the sarcasm. “The case is a cipher, and the key-word is somewhere before us, but we don’t recognize it. ’Pon my soul, it’s dashed annoyin’. . . . Let’s be orderly. Neatness—that’s our desideratum. First, Robin is killed. Next, Sprigg is shot. Then Mrs. Drukker is frightened with a black bishop. After that, Drukker is shoved over a wall. Makin’ four distinct episodes in the murderer’s extravaganza. Three of ’em were carefully planned. One—the leaving of the bishop at Mrs. Drukker’s door—was forced on the murderer, and was therefore decided on without preparation. . . .”
“Clarify your reasoning on that point.”
“Oh, my dear fellow! The conveyor of the black bishop was obviously acting in self-defence. An unexpected danger developed along his line of campaign, and he took this means of averting it. Just before Robin’s death Drukker departed from the archery-room and installed himself in the arbor of the yard, where he could look into the archery-room through the rear window. A little later he saw some one in the room talking to Robin. He returned to his house, and at that moment Robin’s body was thrown on the range. Mrs. Drukker saw it, and at the same time she probably saw Drukker. She screamed—very natural, what? Drukker heard the scream, and told us of it later in an effort to establish an alibi for himself after we’d informed him that Robin had been killed. Thus the murderer learned that Mrs. Drukker had seen something—how much, he didn’t know. But he wasn’t taking any chances. He went to her room at midnight to silence her, and took the bishop to leave beside her body as a signature. But he found the door locked, and left the bishop outside, by way of warning her to say nothing on pain of death. He didn’t know that the poor woman suspected her own son.”
“But why didn’t Drukker tell us whom he saw in the archery-room with Robin?”
“We can only assume that the person was some one whom he couldn’t conceive of as being guilty. And I’m inclined to believe he mentioned the fact to this person and thus sealed his own doom.”
“Assuming the correctness of your theory, where does it lead us?”
“To the one episode that wasn’t elaborately prepared in advance. And when there has been no preparation for a covert act there is pretty sure to be a weakness in one or more of the details.—Now, please note that at the time of each of the three murders any one of the various persons in the drama could have been present. No one had an alibi. That, of course, was cleverly calculated: the murderer chose an hour when all of the actors were, so to speak, waiting in the wings. But that midnight visit! Ah! That was a different matter. There was no time to work out a perfect set of circumstances,—the menace was too immediate. And what was the result? Drukker and Professor Dillard were, apparently, the only persons on hand at midnight. Arnesson and Belle Dillard were supping at the Plaza and didn’t return home until half past twelve. Pardee was hornlocked with Rubinstein over a chess-board from eleven to one. Drukker is now of course eliminated. . . . What’s the answer?”
“I could remind you,” returned Markham irritably, “that the alibis of the others have not been thoroughly checked.”
“Well, well, so you could.” Vance lay back indolently and sent a long regular series of smoke-rings toward the ceiling. Suddenly his body tensed, and with meticulous care he leaned over and put out his cigarette. Then he glanced at his watch and got to his feet. He fixed Markham with a quizzical look.
“Allons, mon vieux. It’s not yet six. Here’s where Arnesson makes himself useful.”