‘The murderer therefore left the footprints as they were, went back down to the rocky area and rowed the boat to the inlet, to see whether he could hear us come looking for Leroux. Fortunately no such thing seemed to be happening. He then went up to the Decagon House and, after checking through the kitchen window whether everybody was really still asleep, he sneaked inside and stuck the plate on Leroux’s door. He gave up on the footprints and left the island. It would have been too dangerous, considering the time of the day as well, to go back to the Blue Mansion once again.’
‘Hmm. So the murderer was here on the island the whole night?’
‘I think he’s been here every night. He arrives on the island by night to watch our movements.’
‘Hiding beneath the kitchen window?’
‘Probably something like that.’
‘And he leaves his boat in the inlet or at the rocky area?’
‘He probably hides it. A small rubber boat can be folded up easily. He could carry it to the grove, or hide it underneath the water with a weight on it.’
‘A rubber boat?’
Poe frowned.
‘Could you get to the mainland with that?’
‘No need to go all the way to the mainland. There’s a perfect hiding place just around the corner.’
‘Cat Island?’
‘Precisely, Cat Island. I think the murderer is camping out there. You could easily row here from that island.’
‘True, that place would suffice.’
‘Let’s reconsider what the murderer did once again.’
Ellery closed the notebook and put it to one side. He produced his deck of blue bicycle cards out of nowhere, put it on the table and played with it as he continued his story.
‘The murderer came here last night from Cat Island. He watched us, hoping for an opportunity to commit his next murder, but he drew a blank and so, this morning, he returned to the rocky area. It was still raining at the time, I think. That’s why there weren’t any footprints of the murderer going from the entrance of the ruins to the staircase.
‘The rain stopped while he was preparing the boat in the rocky area. From then on, footprints would remain intact on the ground. At that point Leroux made his appearance, although I don’t know why he was there at that time.
‘Leroux saw the boat and the murderer. In a panic, the murderer grabbed one of the rocks lying around, chased after Leroux and silenced him. Fearing someone might come running because of Leroux’s cries, he moved his boat to the inlet. He waited a while to see if anyone was out of bed and then sneaked in here to hang the plate up. Something like that.’
Poe’s thumb had not once left his temple. With one elbow on the table, he asked angrily: ‘But Ellery, who is this murderer hiding out on Cat Island?’
‘Nakamura Seiji of course,’ Ellery declared without any hesitation. ‘I’ve been saying that from the start. I wasn’t serious when I said I thought you were a suspect just now.’
‘Suppose I accept the possibility Nakamura Seiji is still alive, for argument’s sake. I don’t know about anyone else, but I can’t see what motive this Seiji could possibly have for wanting to kill all of us? I can’t think of any. Or are you simply saying he’s mad?’
‘A motive? Of course he has one. A strong one.’
‘What?’
‘What do you mean?’ Poe and Van cried out simultaneously, leaning forward.
Ellery’s hands skilfully gathered the cards he had fanned out on the table. ‘We talked about each other’s motives just now, but Nakamura Seiji has a much more obvious one. I only realised itself myself last night, after I’d gone back to my room.’
‘Really?’
‘What is it, Ellery?’
‘Nakamura Chiori. Remember her?’
Silence reigned in the gloomy hall, except for the distant noise of the waves. The rain had eased to a noiseless drizzle.
‘Nakamura Chiori. You mean…?’
Van’s voice had become weak.
‘Yes, our junior member, who died because of our carelessness in January last year. That Nakamura Chiori.’
‘Nakamura—Nakamura Seiji, Nakamura Chiori.’
Poe muttered the words as if he were chanting a spell.
‘But it just can’t be.’
‘It can be and it is. It’s the only reason I can think of. Nakamura Chiori was the daughter of Nakamura Seiji.’
‘So that’s it.’
Poe frowned deeply, tapped a Lark cigarette out of his cigarette case and put it straight in his mouth. Van closed his eyes, his hands on the back of his head. Ellery gathered the cards, placed them on top of the case and continued:
‘It was Nakamura Seiji who committed the murders that happened here on this island six months ago. He burnt someone to serve as his body double, either the missing gardener or maybe he found someone else of similar age and build and the same blood type. Nakamura Seiji is still alive and now he is acting out his revenge for his daughter—.’
At that moment, he was interrupted.
‘Uuurgh!’
An unnatural sound escaped Poe’s throat.
‘What’s wrong?’
‘Poe?’
His chair made a loud noise. Poe’s large body tumbled forwards and fell on the floor.
‘Poe!’
Ellery and Van rushed to him, trying to get him back up. Poe, doubled up with pain, pushed their hands away. And finally, it was over.
In one last violent convulsion, his four limbs thrust out stiffly in the air and he crashed back on the floor face up. That was the fall of Poe.
The Lark cigarette Poe had thrown away after just a single puff was lying on the blue-tiled floor, smoke rising from it. Ellery and Van could only look in shock at the now motionless “Last Victim.”
✦ ✦ ✦
9
It was nearly dusk and the sky was still covered with grey clouds, but it didn’t look as though it would rain. The wind stopped shaking the trees and the noise of the roiling waves had also softened into a melancholic melody.
Poe’s body was carried to his room by the two survivors. On the floor lay the jigsaw puzzle, which had hardly been touched since Van last saw it. The cute, upturned faces of the fox cubs looked terribly sad.
Ellery and Van made sure not to disturb the puzzle and placed Poe’s large body on the bed. Van covered him with a blanket and Ellery closed Poe’s eyes. From his painfully contorted mouth rose a hint of almonds.
After a moment of silent prayer, the two left the room without saying a word.
‘Another time bomb. Damn.’
Ellery’s voice trembled in fury as he trampled on Poe’s cigarette, which had turned to ashes on the floor.
‘One of Poe’s stock of cigarettes was poisoned with prussic acid. He probably sneaked into Poe’s room and injected one of them with a syringe.’
‘Nakamura Seiji?’
‘Who else?’
‘So we were in danger too.’
Van dropped into a chair. Ellery walked to the table and lit the lamp. In the flickering light, mysterious shadows started dancing on the white walls.
‘Nakamura Seiji…,’ muttered Ellery as his eyes focused on the flame.
‘Now I think about it, Van, Nakamura Seiji used to be the owner of this house. He’d naturally know all about the geography of the island and the layout of the buildings, and I’ll bet he also possesses spare keys to all the rooms.’
‘Spare keys?’
‘A master key perhaps. He took it with him after burning down the Blue Mansion and going into hiding. He can enter any room whenever he wants. It was the easiest thing in the world to poison Agatha’s lipstick, or kill Orczy. The same for Poe’s cigarettes. He made sure to stay out of sight and flitted around this building like a shadow. We’re just the poor insects who flew into the trap called Decagon House.’
‘I remember reading somewhere he used to be an architect.’
‘So did I. He might even be the one who designed this place. He was certainly the one who had it built… Perhaps—hold it a second!’
Ellery looked keenly around the hall.
‘What’s wrong, Ellery?’
‘I was just thinking about that cup which was used to poison Carr.’
‘The eleven-sided one?’
‘We now know it wasn’t used as a mark, but do you remember, Van? You asked the question. Why was that cup there in the first place.’
‘Ah, yes, I did.’
‘I answered it was just Seiji’s joke. But I added that it might also have another meaning. Hiding a single eleven-sided object in a house of decagons. Doesn’t that suggest something?’
‘Something eleven-sided inside a decagon? If it is an allusion to anything…’ muttered Van, and his eyes suddenly opened in surprise. ‘It might mean there are eleven rooms here.’
‘Precisely.’ Ellery nodded grimly:
‘I have the same idea. Apart from this central hall, the building consists of ten trapezoidal rooms of equal size. The toilet, bathroom and washstand are one room, the kitchen, the entrance hall and the seven guest rooms make nine more. If there’s one more room hidden here somewhere besides those ten.…’
‘You mean Seiji wasn’t watching us from the kitchen window, but from that secret room?’
‘Precisely.’
‘But where could it be?’
‘Considering the layout of this building, I think it could only be underground. And I have a little idea….’
A smile appeared on Ellery’s lips.
‘…that the eleven-sided cup is the key to the secret room.’