The Button Murder Case

Beneath a dark, damp, filthy bridge, a beggar finds a naked woman's corpse, covered in rats, lying in the spot where he usually sleeps. The body gives off a faint scent of sesame oil, and in her hand is a red button...

At a teahouse, teacher Li Yazhen, rejected by the man she loves, suddenly loses her mind. She insists that travel reporter Jian Dongping take off his coat and return the red button she sewed onto his shirt. That very night, after getting the button back, Li Yazhen is strangled to death outside her home...

After collector Wang Sheng dies of illness, his will leaves his entire collection to industrialist Qiu Yuan, a fellow member of the collectors' club. But what Qiu Yuan receives is ten empty boxes...

Who is the woman found beneath the bridge? Why was she clutching a red button when she died? What does her death have to do with the collectors' club? And what do the buttons mean? Is it just a prank, or a warning that a living person is about to meet their end? Who is the killer?

After confronting the five suspects time and again, Jian Dongping finally finds the killer's weakness. As the killer puts it, this is less a game of deduction than a battle of wits. Everyone has a weakness, and anyone can make a mistake. Can you guess who the killer is?