Night fell quietly over the city. Neon lights flickered on the streets, and a trace of chill lingered in the air, as if foreshadowing something unsettling to come. For ordinary people, midnight was usually the most peaceful time of day. But for some residents, that tranquility had already been shattered—replaced by an inescapable fear.
It all began with a few spine-chilling phone calls. These calls came without warning, reaching the phones of several urban residents. No words were spoken—only a low, continuous frequency echoed through the line. At first, people dismissed them as pranks or technical glitches. However, as the incidents escalated, the calls became so frequent they were impossible to ignore. Soon after receiving the calls, the recipients began dying from sudden heart attacks.
The first victim was a middle-aged man named Li Jianguo, who lived in an apartment in the southern part of the city. The autopsy determined he died from a sudden cardiac arrest. Li, who had a known history of heart problems, had always been cautious about managing his lifestyle to avoid triggering any heart issues. But this death wasn't so simple. When the police arrived at the scene, the only clue was his cellphone—showing a missed call from an unknown number, received just minutes before his heart attack.
Over the next few days, similar cases emerged. Li Jianguo's death was not an isolated incident. Other residents with a history of heart disease also died unexpectedly after receiving similar phone calls. Each victim's phone showed missed calls from the same number.
During the investigation, Su Wanqing noticed a crucial detail. The heart attacks weren't entirely natural—they had been triggered by an external factor. She repeatedly reviewed the recorded audio from the victims' phones and finally detected an abnormality in the frequency patterns. The calls didn't contain speech, only a low-frequency hum, like an audio signal—deeply unsettling and oppressive.
Further analysis revealed that this unique frequency was a form of auditory stimulation capable of affecting people with heart conditions. There appeared to be a subtle link between the frequency and the mechanism that triggered cardiac arrhythmias, causing fatal heart attacks.
"This is a deliberate method of killing," Su Wanqing said grimly. "The audio in these calls is actually a deadly weapon."
Lu Chenzhou nodded in agreement, quickly realizing there had to be a motive behind this. "We need to trace the source of these calls," he said, deciding to personally lead the team investigating the origin.
Their investigation led them to a shocking discovery. All the calls originated from the same number, but it wasn't a regular phone line. It had been disguised to appear like a private number, using specialized equipment to transmit sound frequencies directly over phone lines.
Their search brought them to a telemarketing company called Sunshine Communications. Upon further investigation, they uncovered the mastermind behind the horrifying events: an employee named Zhao Tao.
Zhao Tao had once been a telemarketer, promoting insurance and loan services. His life was full of frustration—he was often insulted and ignored by clients, and endured relentless pressure from both superiors and customers. His pent-up anger and resentment eventually twisted into something darker—a desire for revenge.
In one particular call, Zhao was insulted by a customer who not only acted unreasonably but also humiliated him personally. Unable to bear the degradation, Zhao's suppressed rage turned into a plan for retribution. At first, it was just a fantasy—a wish to make these people suffer. But over time, the thought became an obsession, and he resolved to act.
Using his knowledge of audio signals and the company's phone system, Zhao created a special frequency. He transmitted it through the phone lines, targeting clients with known heart conditions. Each time, he selected a different target. The frequency would trigger their heart problems upon receiving the call, leading to sudden cardiac death.
"He turned the phone into a weapon," Lu Chenzhou said solemnly. "And his chosen victims were those helpless people who once humiliated him."
Zhao's revenge didn't bring him the satisfaction he expected. Instead, it drove him further into madness. He began to derive a twisted pleasure from hearing the victims' final gasps over the phone. Each "success" only deepened his addiction to this cruel game, until he lost all control over his actions.
The police eventually arrested Zhao and uncovered the full truth behind this chilling case. During interrogation, Zhao confessed and explained his motive. Though he tried to justify himself with claims of psychological stress and past humiliation, the evidence painted a picture of cold-blooded murder.
The case sparked widespread public concern over the telemarketing industry and raised awareness about the misuse of technology and the dangers of unresolved psychological trauma. Zhao Tao's actions weren't just a manifestation of his twisted inner world—they were a warning: even the most mundane tools of daily life could become lethal weapons.
After the case closed, Su Wanqing and Lu Chenzhou stood at the crime scene, reflecting on the tragic chain of events. Though they had found the truth, a chilling sense of unease still lingered in their hearts. Was the true cost of revenge a damned soul—or the innocent lives lost along the way? Perhaps only Zhao Tao could answer that question.
"Midnight's ringtone is always the most unsettling," Su Wanqing murmured. "But what's even more terrifying is the pain hidden behind it—pain that may never heal."
Lu Chenzhou didn't respond. He simply stared into the distant night sky, silently contemplating everything that had happened.