The country's crime rate rapidly grows until an unknown detective starts to give notes where he both taunts and helps the police.

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Jasper Heaven traveled around the country with his grandmother Reneat, who was a police consultant in her youth. They arrive in a town where a railway worker and their lover are murdered. The local police's investigation was questionable at least until the famous detective's card starts to show up. Can the police solve the case alone or they will put more effort into finding out who this secretive detective is?