Don't Laugh

Police Inspector Mc Ivan and the other policemen in the little town of Gensan are having headaches due to the continued killing in their town. The hardest part is, it was all a clean killing, no evidence was seen. Only a note on every victim's hand saying, "Don't Laugh". And there is no connection to every person who was killed by the suspect. Until one day, another murder took place, and it was the son of Kissa-whom Ivan was courting and because of that, he was burning in determination to find the culprit. Will he be able to do it?