Just as he expected, the plot in this world would take place in a prison. And it was not an ordinary prison either.
Nightingale Prison was the most terrifying and mysterious prison in the world which was built a few hundred meters underground. At first, it was only an ordinary prison used to confine the most vicious criminals sentenced with life imprisonment or death-row prisoners.
However, it was unknown what happened one day but a great chaos suddenly broke out inside. Everyone — including the prisoners, wardens and staff — seemed to have been possessed by a ghost and started to attack each other in the most brutal way.
