杜三郎为了躲债搬进了一处隐秘的居所，但最终还是被债主中村发现了。某夜，十点时分，杜三郎在客厅里沉浸于电视节目之中，而中村却突然闯入。他咀嚼着口香糖，提出了偿还债款的要求。

杜三郎一边恳求他宽限时间，一边从冰箱里取出啤酒，将其倒入杯中邀请他饮用。在中村不备之际，他趁机拿起空啤酒瓶击打他的头部。结果，中村因意外的一击直接失去了生命力。

杜三郎迅速将汽车开到车库，又将尸体装入行李箱运往S公园远离市区的地方，然后将尸体扔进池塘深处。凌晨两点回到家后，他又彻底清理房间，每个细节都极尽完美，无一遗漏地擦拭桌椅、啤酒杯、大门把手及门铃按键，以消除任何可能留下的痕迹。

由于过度紧张的神经状态，使得杜三郎直至第二天傍晚才勉强入睡。当下一次门铃响起时，他再次战栗不安地打开大门，却看到面前站着两个陌生人，他们询问昨晚是否有名叫中村的人光临过，并且提到在S公园附近发现了一个尸体，上衣口袋内有一块火柴盒，其背面刻有杜三郎家的地址。

尽管面对他们冷酷的笑容和疑虑，杜三郎仍旧坚称昨晚没有人来访，也与已久未见面的中村无涉。但是，这些人的眼睛透露出一种难以掩饰的轻蔑和讽刺，因为他们已经在上午先前访问过这个地方，只是在大门前捡到了一个小玻璃瓶，它似乎隐藏着重要线索。

当这些人从衣袋里掏出那个小玻璃瓶，让它悬挂在空气中的时候，Du Three's eyes widened in horror as he realized that the game was up. The small glass bottle contained nothing more than a few strands of sugar and some saliva, but it was enough to condemn him.

The truth was finally revealed: the sugary residue on the floor had been accidentally dropped by Middle Village when he came to visit Du Three. The tiny particles of sugar were still moist with his saliva and bore an unmistakable impression of his teeth. Moreover, there was no dust or dirt on them, indicating they were freshly dropped.

Du Three had overlooked this crucial detail during his frantic efforts to cover his tracks after committing the crime.