“It’s conceivable.”
Larch shrugged. “Well, then; that’s obviously what he did. The rest ties up. He’s the father of the girl Stan killed. The accident probably tipped his nut and he’s been scheming ever since to take revenge. The anniversary of her death would be just the day.”
“The motive’s strong enough,” Purbright agreed. “What about opportunity?”
“Grope had that, all right. He hangs on here until all sorts of odd times. I’ve known him sleep all night in one of the seats. He could easily have slipped out to that caravan, got the window open as you suggested, popped the bomb inside and scarpered without anyone being the wiser. His old woman doesn’t keep tabs on him.”
“And the earlier explosions?”
Larch considered. “Aye, well I suppose he must have worked those too. The same argument applies, though. Grope always had a good excuse for being out at night.”
Cradling his shins in clasped hands, Purbright drew up his knees and pensively rested his chin upon them. When again he began to speak, his voice was flattened by the posture and Larch had to bend forward to catch what he said.
“The idea of setting off a chain of explosions in the form of practical jokes for which Biggadyke might be blamed was clever. It had precisely the intended effect. A good many minds were already made up by the time the last explosion was fixed—the only one that really mattered. Even the coroner, who’s no fool, was prepared to assume what the murderer intended him to assume. It’s important, I think, to grasp that planning of this order indicated an altogether exceptional mind. Unless we do, we might easily fall into whatever second or third line traps that so gifted a gentleman would undoubtedy have devised.”
“I would hardly call Grope gifted,” said Larch, after pausing to wonder what Purbright was getting at.
“You wouldn’t?”
“He’s a bit peculiar, but not in the way that would make him a genius. No, this business has just turned out luckily for him, that’s all. You’re reading too much clever stuff into it.”
The stalls door opened and one of the charwomen waddled through. She glanced blankly at the waiting policemen and went into a closet. They could hear her singing a wordless, wavering dirge.
“Will he be long, do you think?” Purbright asked.
Larch rose immediately. “I’ll root him out.”
“No; don’t let’s ruffle the fellow. If he’s the one you want, it’s going to be difficult enough to lead him into court in a friendly way. Pushing him would be hopeless.”
Larch smiled sourly, but he sat down again. “Grope’s no master mind. I wish you’d get that idea out of your head. I tell you once he sees that we know what’s what, he’ll give us all we want.”
“It’s your case.”
“I know these people.” Larch waved his hand. “They're incapable of elaborate planning and plotting. You said something just now about traps—second and third line traps, wasn’t that it?” He waited for Purbright to nod. “Yes, well it’s all so much fanny. What did you mean.”
Purbright thought that behind the bluster he detected anxiety. He explained quietly.
“It seems to me, d’you know, that whoever removed Mr Biggadyke took good care to build around the killing a number of defences in depth, as it were. Or traps, if you like, in which the inevitable investigation would be caught and either made harmless or turned away against somebody else.
“The first and most intelligently devised trap was very nearly successful in ending the matter. Almost everyone gleefully leaped into it. As I said before, it was the assumption that Biggadyke had killed himself by his own ridiculous prank-playing.
“Certain knowledge was needed for that plan. The murderer must have been aware firstly of Biggadyke’s reputation as a practical joker—no difficulty there, of course. Secondly, he must have had a good idea of the sort of targets Biggadyke would choose. You’ll admit the selection was most convincing. The third piece of knowledge could have been acquired only by careful observation—or else”—Purbright regarded Larch steadily—“by receiving or overhearing a confidence. I’m talking now of Biggadyke’s private arrangements for Tuesday nights, his caravan appointments.
“So much for the preparation of trap number one. All very ingenious and thorough. But there was one danger...” He paused.
“Your wife, Mr Larch.”
The Chief Inspector said nothing. He slowly brought up his hand and looked at the open palm as if examining a derisory tip.
“The odds were that she would keep clear, as indeed she has,” Purbright went on. “But there was always the possibility of her telling the truth about those Tuesday nights. Once that was out, the misadventure set-up would collapse. And the fact of murder would be left in broad view.
“As it happens, we spotted it from a completely different direction. But that was by the sheer luck of Kebble’s having seized on that queer obituary.
“The murderer was intelligent enough to realize that by the very act of intervening and thereby destroying his first defence Mrs Larch would prove the perfect decoy into trap number two. Once she allowed her relationship with Biggadyke to be known, suspicion would automatically fall on the man with the best reason in the world for wishing her lover dead—the man who, by curious coincidence, is another of the town’s regular Tuesday night absentees—and, to crown it all, the man who is an expert in the use of explosives, a quantity of which happens to have been missed from the depot where he is a part-time instructor.”
Larch drew in a long, rustling breath. The grey face had whitened round the mouth. Yet he forced his thin, humourless smile. “We’d better get the bastard pulled in before you make me confess.”
“Mrs Weaver!”
Both men looked to see the face of Mr Grope thrust through the auditorium door. Again rose the querulous bleat: “Mrs We-e-e-eaver!”
There was a clatter of buckets and dustpans and the charwoman emerged from her haven, blinking and hostile.
“Kindly bring a paper bag, Mrs Weaver. Third one-and-nine from the radiator on the clock side. Seventh seat in.”
The woman glowered. “That Mr Follicle’s not been taking ’is bandage off again?”
“Looks like it, Mrs Weaver.”
Grope spotted Purbright and Larch as they rose. He shook his head. “You mustn’t start the queue inside, sir,” he said reprovingly, adding after further scrutiny, “You are patrons, I suppose?”
“No, Mr Grope, we are not,” retorted Larch. “I think you know who I am. Would you mind coming over here a minute?”
Grope lumbered up, looking from one to the other. Mrs Weaver, incurious, padded purposefully away. “Now then,” Larch said, “you’ll kindly do your duty by answering a few questions. You’ve nothing to be nervous about if you tell the truth.”
“What kind of questions?” asked Grope sullenly.
“All kinds.” Larch was plunging into the interview with a horrid briskness that prompted Purbright to nudge his arm and frown. Larch misinterpreted this as a request to be introduced. “Oh, yes; this is a colleague of mine. Inspector Purbright. And if you think my questions are rough, just you wait until he starts.”