Who?

The curse

'What, you hid this fact that you have 2 children even from me.' Robin was shocked. He couldn't believe that his best friend, who never hid anything from him since childhood hid the fact that he had 2 children. 'Me and Rose have 2 children- Sarah and Jacob, Sarah was born on 4th February 2015 and Jacob was born on 17th September 2016.' Noah answered with tears in his eyes. 'There was a curse on the ring that any person who keeps it with them can never attain peace of mind or happiness, after I assumed the responsibility of the Spartan Ring, things went well only for a short while. After the birth of Jacob, things started going upside down. One fine day, I received a letter from an anonymous person, the letter warned me from discovering the truth behind the ring, it said that if I tried to do anything stupid, that person would kill my family in front of my own eyes.' Noah was almost choking by now, asked for a glass of water. He kept on thinking about his children and wondered whether he should bring them back. 'One day, while Sarah was playing in the yard, suddenly she started shouting, we went out and saw that someone had left a deep cut on her left leg, she was bleeding heavily. It was a knife cut. She had to be taken to the hospital, after she recovered from the trauma of that incident, we asked her about who did it, she told us that a knife was thrown at her leg from up above. We were horrified that the person who wrote the letter would actually go this far. Rose was extremely worried about their safety, she suggested that we send them to the countryside to her parents' home. I agreed because I too was worried about their safety. I suggested that nobody other than her parents should know about the reason why we were sending them away.' Noah had a worried look on his face. 'Don't worry Noah, after all this is over, we'll bring your kids home.' Robin comforted him.
'Thanks, Robin, But I don't know whether all this will ever be over or not.' 'Why did that person kill your family that night?' Woojin asked Noah. 'Yesterday night, my father was about to tell me the truth of the ring.' 'How would that person know that your father was about to tell you the truth.' 'I had received another letter 5 days ago, it said that the writer would give me 7 days to know the truth and stop him from doing something extremely horrible which could threaten the whole world, but he didn't mention what exactly. I arranged a meeting with my father scheduled yesterday night, but while waiting for them, I was thinking about the old mansion in Julius avenue, I had heard my father say that it hides very deep and dark secrets, I ran towards it, I hope that I hadn't. I went there and it looked like a basement of some sort even though it was above the ground. There was a note pasted on the wall, it said "You shouldn't have come here, now your family is in danger." I immediately ran towards my home, I ran faster than ever. I reached my home and......' Noah broke down at that very moment. 'It's ok Noah, I know what you must be going through. Even I lost my parents at a young age.' 'Not just he killed all of them, but he wrote on Rose's, Julia and Robert's body: Your Children are next, 3 days to go, Earth will be....., he left blank space after that.' 'I know where all the answers lie, we must make our way to that mansion in Julius avenue.' Woojin said after a brief moment of silence