‘Sorry I’m late,’ the junior detective said, taking a seat next to Kusanagi.
‘What’s the word?’ Kusanagi asked her.
She nodded. ‘Good news. They found traces with the exact same composition.’
‘No kidding,’ Kusanagi breathed.
They had sent the empty can from Junko Tsukui’s mother’s house to Spring-8 for testing, and the lab had detected trace amounts of the exact arsenous acid that was used to kill Yoshitaka Mashiba. This backed up Ayane Mashiba’s confession that she had put the poison Junko sent her through the mail into the water-filtration system.
‘Sounds like the case is closed,’ Yukawa said.
‘That it is,’ Kusanagi agreed. ‘Well, since we’re all here now, how about a toast?’ He called over the waiter and ordered champagne. ‘I have to admit, you really saved my ass this time, Yukawa. Tonight’s on me. Drink all you like.’
Yukawa raised an eyebrow. ‘“This time”? Don’t you mean “again”? And I was under the impression that it was Ms Utsumi I was helping, not you.’
‘Details, details. Hey, here’s the champagne.’
The three brought their glasses together in time with Kusanagi’s shout of ‘Kanpai!’
‘What impressed me most was that you held onto that thing,’ Yukawa said after they had all taken a drink.
‘What thing?’ Kusanagi asked.
‘The empty can Mrs Mashiba had been using to water her flowers.’
‘Oh, that,’ Kusanagi said, a sour look coming over his face. He dropped his gaze to the table.
‘I knew you offered to water her plants for her, but I hadn’t heard about the big new watering can. Regardless, why did you hold onto the old one? Utsumi tells me you had it in your desk drawer.’
Kusanagi glared at the junior detective, but she looked away.
‘Well … I guess you could call it intuition,’ he said at last.
‘Ah, the famous detective’s intuition?’
‘That’s right. Besides, you never know what might become evidence, so you don’t throw away anything until the case is closed. That’s standard operating procedure.’
‘Standard procedure, right,’ Yukawa said with a shrug, taking another sip of his champagne. ‘I’d assumed you held onto it as some kind of keepsake.’
‘What’s that supposed to mean?’
‘Nothing. Forget about it.’
‘Actually,’ Utsumi joined in, ‘I had a question I wanted to ask you, Professor.’
‘By all means.’
‘How did you figure out what trick she used? Did it just come to you at some point?’
Yukawa gave a soft sigh. ‘Things don’t just “come” to me. The idea occurred after I made several observations, and gave it a great deal of thought. The first thing that tipped me off was the condition of the water filter. I saw it with my own eyes, and it was exceedingly clear that no one had touched it for quite some time.’
‘Right, which is why we couldn’t figure out how she had got the poison in there.’
‘Yes; except I started to wonder exactly why the outside of the filter was so dusty. From what you told me, Mrs Mashiba sounded like a fairly fastidious person. Wasn’t it her failure to put away her champagne flutes that first made you suspect her, Utsumi? If your assessment was accurate, then I would expect a woman like that to keep things pretty neat and tidy, even under the sink.’
Utsumi’s eyes widened. It seemed like an obvious observation after the fact.
‘It got me thinking. What if she had left it that way, covered with dust, on purpose? And if so, why? That’s when my idea occurred to me.’
Utsumi stared at the physicist’s face, shaking her head. ‘Well, I’m impressed.’
‘There’s nothing to be impressed with – unless you mean you’re impressed with Mrs Mashiba. Only a woman could come up with a trick so illogical, so full of contradictions, and so perfect.’
‘Speaking of contradictions, Hiromi Wakayama apparently decided to keep her child.’
Yukawa shot Utsumi a suspicious look. ‘Isn’t that straightforward maternal instinct?’
‘Yes, but it was Ayane Mashiba who told her she should.’
The physicist’s expression froze for a moment. Then he slowly shook his head. ‘That … is a contradiction. I don’t understand.’
‘That’s a woman for you,’ Utsumi offered.
‘I see. Then I’d have to say that it’s nothing less than a miracle we were able to solve this case rationally. Don’t you think—’ Yukawa turned to Kusanagi, and cut himself off.
Utsumi glanced at the detective beside her. His head was hanging. He was sound asleep.
‘No wonder he’s exhausted,’ Yukawa said quietly, with a look at Utsumi. ‘With the unravelling of the perfect crime came the unravelling of his affection. Let’s let him sleep it off.’
He raised his glass.