DURING A ROUTINE POLICE CHECK, A MURDER IS DISCOVERED ON AN OMNI BUS TRAVELING FROM CHENNAI TO COIMBATORE. SHOCKINGLY, THE CRIME TOOK PLACE ON A MOVING BUS CARRYING 25 PASSENGERS, YET NO ONE NOTICED ANYTHING UNUSUAL. INSPECTOR CASTRO FINDS IT HARD TO BELIEVE THAT SUCH A MURDER COULD OCCUR UNNOTICED. THE STORY FOLLOWS HIS INVESTIGATION AS HE WORKS TO IDENTIFY THE KILLER BEFORE DAWN, UNRAVELING THE MYSTERY PIECE BY PIECE.