民间奇闻怪事1000例免费小岛的诡计
段五郎接到研究所所长小岛博士的电话，说他刚接到一个恫吓电话，要他把一份绝密文件交出来，否则就要他的老命。小岛博士没有办法，只好求救段五郎，请他晚上8点到他家，再详细谈谈情况。
晚上8时，段五郎准时赶到了小岛家里，按了门铃，却不见回音，他见房间里灯亮着，无意之中拧了一下把手，发现门竟是开着的。段五郎冲进屋里一看，只见小岛博士昏倒在沙发下面，旁边扔着一块散发着药味的手帕。这时，只见小岛博士慢慢地睁开了朦胧的双眼，本能地摸了摸自己的衣服口袋，失声地叫了起来：“完了，那份绝密文件被人抢走了！”
这份绝密文件据说是一项革命性的科学研究成果，对于整个行业都有重大影响，小岛博士深知其重要性，所以一直格外谨慎保护它。在这个紧要关头，他只得向心腹助手求助。
“那是什么人?什么时候？”段五郎急忙问道，小岛看了一眼手表，说：“大概30分钟前，我一边看电视一边吃苹果，一听到门铃响，我以为是您来了。不料一开门，我被两个男人用枪顶了回来，他们立即用手帕堵住我的嘴和鼻子，以后我就什么也不知道了。”
果然，小岛咬过的一半苹果正滚在电视机下面，电视机电源已断了。segment Five picked up the apple from under the TV, took a glance and said, “Doctor, you sold it to them yourself!”
Island looked at him in shock and replied, “I? How could I do that!” Segment Five coldly looked at Island and threw something on his face. Island saw what it was - a large bag of cash hidden in the refrigerator.
Segment Five had unraveled Island's cunning plan by using an ordinary apple. The apple contained a substance called oxidized malic acid which is normally sealed within cells but when exposed to air would react with oxygen causing discoloration. If true as claimed by Island that he was knocked out 30 minutes earlier, then the color of the apple should have changed.
The story reveals how Segment Five used this seemingly insignificant detail to expose Dr. Island's scheme. It demonstrates how sometimes even small details can lead to major revelations in solving mysteries and unraveling deceitful plots.