Holly, Amanda and Peter won a competition on the radio and have been invited to a Mystery Weekend at Granville Towers but it's not all fun and games as there's a real mystery that needs solving. Will Holly, Amanda and Peter be able to solve it? This is by far the best in the series for me, it kept me intrigued because it was really interesting and every clue led to another which made it fun. The way they take their time and think about it rather than rushing to figure it out is great.