The third and most mysterious Monstacademy Mystery yet!
There's a traitor at Monstacademy!
When Trixie returns after being suspended, her best friend Gloria doesn't seem herself. To make matters worse, the vampire is suddenly best friends with an exciting new monster. Is the new girl all that she seems, or are the Mean Ghouls up to no good?
When the most important monster in the country pays Monstacademy a visit, the threat of their school closing hangs over Trixie and her friends like a black cloud. To make matters even worse, there's a traitor in the ranks. Who is making things go wrong at just the right time? It's a mystery that Trixie and Colin will have to solve on their own, unless they can convince Gloria to help them save the day once again.
Will a surprise visit from the Grand High Monster spell the end for Monstacademy?