"Certainly not. Why should I? It wasn't an incident I'm proud of."
"We've got to think of all the angles."
"All I can say is what I know to be the truth," Milo stressed in a more defensive tone. "You can see for yourself that when I'm aboard the boat, it's just about impossible for anyone else to come in here without my knowing. You can hear every step, and there's nowhere to hide. It's all open-plan. Anyway, the cupboards are far too small to hide anyone."
"What exactly are you driving at?"
"If the murderer found some way of stowing away while I was still here, and remained hidden when I locked up, it" would be possible to unbolt the door at the far end-unbolt it from the inside-and admit the victim."
Diamond almost snapped his fingers in triumph. Then, as the flaw in the revelation occurred to him, he converted the gesture into scratching his right earlobe. "But when you and Wigfull entered the boat, it was bolted from the inside at that end and padlocked outside at the other. Unless the killer was still aboard, it couldn't have happened."
"There you go," said Milo with an air of resignation. "I can assure you, there wasn't anyone here except poor old Sid. I'm as confused as anyone by all this."
"And as you remarked just now, there's nowhere to hide. Everything folds against the walls. The only lockers are outside the cabin, back at the stern end." Diamond paused, watching Milo. "The crucial question is whether your memory is reliable when you say you locked the boat."
"Of course it is!" Milo said petulantly. "I remember rattling the damned padlock, testing it with my hand to be sure it was secure. And it was. Later, when I returned with your colleague, Mr. Wigfull, I unlocked with my own key and had the shock of my life when I saw what was inside. It's impossible, but it happened. I am at a total loss to account for it. You need Dr. Fell for this."
"Who's he?"
"Dickson Carr's detective."
"A detective in a book? Great."
"Someone of his caliber, at any rate."
"Thanks for the vote of confidence," said Diamond. "Well, I think we need someone smarter than Dr. Fell. I've been through that chapter on the locked room lecture, and it's no help. I ask you. You've studied it yourself. This is a puzzle that defies all Dr. Fell's explanations."
Milo nodded. "I have to agree with you."
"And the locked room is only part of the mystery. What was Sid's reason for coming here?"
"I haven't the foggiest," Milo answered with a shrug. "He wasn't in the habit of visiting me. Besides, he knew I wouldn't be here. I told everyone I was going straight to the police station to hand in the Penny Black. Do you think the murderer lured him to his death?"
Diamond didn't want to trade theories any longer. "Look, why don't you pick out the clothes you need? I'll take a stroll along the towpath and see you in ten minutes."
He needed more time for reflection. Milo, surely, was a reliable witness. This, after all, was the one member of the Bloodhounds who couldn't have murdered Towers. Yet there was still a doubt. Any lawyer will tell you that witnesses tend to present themselves and their actions in the most favorable light, sometimes obscuring serious flaws in their evidence. Suppose Milo hadn't after all locked the narrowboat before leaving for the meeting. Suppose through carelessness or over-confidence he had left the padlock hanging from the staple still unfastened. At first he may have decided not to mention it; no one wants to admit to negligence, particularly to the police. Later, as the investigation proceeded, he would find it increasingly embarrassing. An act of carelessness would grow into a deception. He might even have lied to cover it up.
Human frailty seemed a stronger bet than mechanical wizardry. Ingenious locked room puzzles were the province of detective story writers.
He went across to the divers. They had unpeeled their wet suits and were stacking their van. He had another job for them tomorrow, he told them, further along, by the Avoncliff Aqueduct. A bunch of keys. They didn't sound overjoyed. With a wink at the constable on duty, he stepped briskly along the towpath. This stretch of waterway now used for mooring was historically the route taken by the barges transporting coal from the Somerset mines. Much more narrow than the main canal, almost two centuries old and edged with ancient flag-stones, it had its own character, though the aluminum lift-bridge where it joined the Kennet and Avon was clearly a modern replacement. He stood for a moment staring at this bridge, deciding how the lifting mechanism worked. Clearly it had to be raised for anything the size of a narrowboat to pass under. There were counterweights projecting from the fulcrum, but the walkway was bolted down on the opposite side. He hauled on it to make sure. At this late hour nothing was about to pass into the boatyard, so his curiosity had to be set aside. He turned and started back toward the solitary policeman.
The question of most interest to him now was the one Milo had raised only a few minutes ago: What could have induced Sid Towers to visit the Mrs. Hudson? It was strange behavior considering that Milo himself was not going to be present. Why visit a locked boat after dark? One possible explanation was that the murderer had suggested meeting him there. If it was a trap, what was the bait? Or was it a threat? Maybe Sid had been under some pressure to obey the summons.
Blackmail?
He stepped aboard the narrowboat and found Milo in the cabin filling carrier bags with clothes. "I'm about ready."
"Good. It's cold in here. I don't know how you put up with it."
"Well, I've got no heating on. Normally it can be really snug."
"I walked to the end of the canal," said Diamond. "As far as that lift-bridge. It is a lift-bridge?"
"Oh, yes. It has to be raised each time a boat goes out."
"How do you lift it, then? So far as I can tell, the thing is bolted down."
"It is. We unfasten it with a windlass. Everyone using the moorings has one. You get one from the office."
"Like a spanner, you mean?"
"Yes."
"That explains it, then. Let me help you with those." He picked up one of the bags. "Ready to leave?"
"Will the constable lock up?"
"We'll do it."
They emerged from the cabin. Diamond pressed the strap over the staple and closed the padlock over it. "Where do you keep the windlass? I wouldn't mind seeing what it looks like."
"It's in the locker on the right. I keep the tiller in there with it."
Diamond pulled up the lid of the locker and peered at the collection of tools. "I can see the tiller. Can't see anything like a windlass."
Milo bent over and shifted the contents about. "Well, that's a damned liberty. It's gone. Someone must have pinched it."
"Are you sure?"
"It's always here."
"What size and weight is this windlass?" Diamond asked.
Milo extended his hands about eight inches. "It's iron. Not a thing you'd put in your pocket and forget about."
"Heavy enough to crack a man over the head and kill him?"
"Good Lord. Is that possible?"
"Problems?" said Julie, seated at a desk near the door.
Diamond made a sound deep in his throat like a growl, pushed a computer keyboard aside, and perched his rear on one of the desks in the incident room. The civilian staff had finished work for the day.
He sighed. "No worse than yesterday. I'm boxed in, Julie. I don't care for it."
"Because of the way the body was found?"
"The whole shooting match. The bloody riddles. The missing Penny Black. This ridiculous Bloodhounds club. It's straight out of a whodunit. I'm a career detective, not a poncy Frenchman with spats and a walking stick."
"Belgian."
"What?"
"Hercule Poirot is a Belgian."
"I don't care if he's from Outer Mongolia. He's a figment of some writer's imagination-that's the point. Everything up to now is detective story stuff from sixty years ago. It shouldn't be happening in the real world. I'm being asked to deal with a locked room murder, for Christ's sake. If I crack it-I mean when I crack it-what am I going to be faced with next? Invisible ink?"