“What about the padlock? Did Forensics take it away?”
“Nobody said anything about a padlock, but I’ll ask.”
The next thing Yukawa turned his attention to was the door handle. He looked at the handles on both sides of the door.
“Could I send the officer on sentry duty to go buy something?” Yukawa asked.
“Buy something?”
“Yes, I want him to get me a set of screwdrivers.”
“Screwdrivers? Why?”
“Just something I need to check. If he can’t go, I’ll do it myself.” Yukawa’s gaze was still fixed on the metal door handle. In profile, he looked every inch the scientist.
“Fine. I’ll tell him.”
Kusanagi went outside and had a word with the policeman who was a little puzzled but agreed to go. When Kusanagi came back inside, he found Yukawa sitting on the bed, sunk in silent thought.
“He’ll be right back with what you need.”
“Very good of him,” said Yukawa, not opening his eyes. “There was no evidence of resistance, was there?”
“I’m sorry?”
“Hasunuma. There were no indications of him having struggled or fought back?”
“No, none. He was just lying on top of his quilt. His clothes weren’t even disheveled.”
Yukawa opened his eyes, rose to his feet, pushed the sliding door shut, then ran his eyes around the whole doorframe.
“What are you checking for?”
“Airtightness. I’m trying to see how much air can get in and out when the door’s fully closed.” Yukawa slid the door back open. “Even when you push it shut as hard as you can, there are still lots of gaps between the door and the frame. It’s not remotely airtight. It would be different if you sealed it up with duct tape.”
“And if there was a high level of airtightness?”
“If you could make the room fully airtight, then all you’d need to do would be to shut and lock the door while Hasunuma was asleep inside. With no oxygen going in, the room would fill up with carbon dioxide and he would eventually suffocate.”
“I see.” Kusanagi cocked his head to one side. “But wouldn’t he wake up if he was having trouble breathing?”
“Yes, he’d definitely regain consciousness,” said Yukawa, po-faced. “The room is small, but not so small that you would suddenly run out of oxygen. Hasunuma would still be capable of moving, so he would do his best to open the door. If he found it locked, he would try to smash it down.”
“That theory’s no good. It doesn’t fit with the facts.”
Yukawa was wagging a finger in front of Kusanagi’s face.
“You’re getting ahead of yourself as usual. There’s an order for doing things. All I did was propose the simplest possible solution first. Now I’m going to gradually build on that to develop new ideas. We know that simply sealing the door shut isn’t going to produce a sudden oxygen deficit. How to produce that is the next question we need to consider.”
“So how do you do it?”
Yukawa frowned. “Aren’t you tempted to try and figure it out for yourself?”
“What do you think I brought you here for?”
Yukawa shook his head in a theatrical display of disappointment. “What about getting Hasunuma to take a sleeping draught? Have you had any thoughts about that?”
“No, I’m stumped there, too.” Kusanagi held both hands out, palms upward. “I have no idea when, where, or how he was fed the stuff.”
Yukawa pointed to one corner of the room where there was a small refrigerator. “Did you check the contents?”
“Of course. Forensics removed and examined everything that was inside it. They didn’t find anything suspicious.”
The only drinks they had found in the refrigerator were an open bottle of oolong tea and an open bottle of water. Neither of them contained any sleeping medication.
“Still, there is one thing that’s bothering me,” Kusanagi said. “According to the pathologist, it’s highly likely that Hasunuma was drinking beer. His blood alcohol was a little on the high side. We know that Hasunuma was quite a drinker, so if someone offered him a beer, chances are he would drink it. To some extent, it would depend on who offered it to him.”
“What about the occupant of the apartment? It would be easy enough for him to get Hasunuma to ingest something laced with a sedative.”
“True, but he has no motive,” Kusanagi replied smartly. He had already thought that possibility through. “There is no connection whatsoever linking Eiji Masumura and Saori Namiki. Masumura and Hasunuma actually met almost a year before Saori was murdered. I trawled through his past and couldn’t find any kind of link.”
“What if the killer bribed Masumura to spike his drink... or would that be too risky?”
“Too risky. Masumura could blow the whistle anytime he chose. And even if he didn’t say anything, he could always ask for more money.”
“That’s true,” Yukawa murmured, resuming his inspection of the little room.
A moment later, the young policeman popped his head around the door. “I’m back. This is what I got. Will it be okay?”
He held out a plastic case containing multiple varieties of screwdrivers. “That’s more than good enough. Thank you,” said Yukawa, taking it from him.
Yukawa sat on the floor by the sliding door of the storeroom and used one of the screwdrivers to loosen the screws that held the door handle in place. He was a scientist and obviously used to working with his hands.
“What are you doing?”
“Wait and see.”
Yukawa needed only two or three minutes to detach the handle fittings from both sides of the door, exposing a square hole in the wood beneath.
“As I thought.” Yukawa smiled complacently as he put his eye to the hole.
“What’s this all about? Come on, tell me.”
“It’s so blindingly obvious, I really shouldn’t need to.”
Yukawa had slithered off to one side, so Kusanagi crouched down and peered through the hole. He could see to the far back wall of the small room.
“I can see right through it.”
“Indeed, you can. When carpenters fit handles to doors, they seldom drill a hole right through. This door, however, is on the thin side, so they did.”
“I can see that, but what’s your point?”
“Do you know the mystery novel The Judas Window by John Dickson Carr?”
“Never heard of it.”
“Why am I not surprised?” said Yukawa, shaking his head. “What I’m saying is that this door contains a little secret window.” Yukawa pulled the door shut. “Even if you shut the door like this, you can exploit this window to do something to the person inside.”
“What can you do with a hole this small?”
“I told you a minute ago. It’s about causing a sudden oxygen deficit. I can think of several ways to do it, using this hole.”
“For example?”
“For example, by sucking out the oxygen through it.”
“Huh?”
“You could use an aspirator of the kind found in vacuum cleaners. You couldn’t make a perfect vacuum, but I suspect you could probably make the air very thin indeed.”
“For God’s sake, Yukawa?” Kusanagi peered into the professor’s eyes behind the rimless spectacles. “Are you serious?”
“I haven’t got the time to fool around.”
“Do you think that method could work?”
“Probably not. If that level of thinness of air was enough to cause asphyxiation, then all the world’s mountain climbers would probably be dead.”
Kusanagi felt himself go weak at the knees with disappointment. He braced himself. If he got upset by this sort of thing, he should stay away from Yukawa altogether. “And what’s your next idea?”