Leung (Simon Yam) is doing God's Work. He's an Angel of Mercy. He's saving souls, delivering everlasting peace to the tormented.
He's also a Serial Killer.
Police psychologist Cheung (Kenny Wong) is assigned to the case, and discovers Leung's hunting ground: an online web forum for people planning to kill themselves. Suicide is a sin, says Leung, so it's not murder - he's saving their eternal souls. And he's not done yet.