The Revenge Protocol

Something strange had begun to appear in the city.
No one knew when it started, and no one understood why.
A quiet place... an empty room... a bathroom where no one was supposed to be watching. And then suddenly, someone would notice it - a glass jar placed carefully as if it had always been there.
Inside the jar floated something that made people freeze in horror.
There were no sounds of struggle.
No witnesses.
No clues left behind.
Only one small, almost invisible mark drawn beneath the jar - a symbol that no one seemed to understand.
At first, it looked like a random crime.
But slowly, a question began to grow in the shadows.
Was someone sending a message?
Or was this only the beginning of something far more dangerous?