Like teenagers nowadays, year-four university students Rain, Eva, Mandy and Violet's is addicted to sending SMS. One night, Rain receives Eva's SMS "Help me!", then she finds Eva has been brutally murdered and her mobile phone starts to beep with a new incoming SMS—GAME OVER….. Later Rain receives SMS from Eva's mobile phone, "Do you know what the 19th Gate of Hell is?" Chinese mythology says that there are 18 levels in hell--how then can there be a 19th level?

In order to find out the truth, Rain, Mandy and Violet start to play this mobile game, Mandy and Violet terminate one by one on different levels of the game – and die horrible deaths in the real world. The final SMS on their phones reads – GAME OVER…Segregate Yip takes up this case, is this done by a homicidal maniac or a game designed by the "hell".