The Phone Rings - Zangha - زنگ‌ها

In a western city, some people are threatened by a phone call. The police step in and start investigating. Murders take place as said. A newspaper designate a special reporter to pursue the murders. The police have everything under surveillance and suspect everybody. The reporter will be the target of the murderer(s) himself. However, while escaping from the murderer(s), he drowns into the sea and dies.