I really like this series and this is another fun addition - although to be fair, Mel just shouldn't have gone to the reunion and her friends shouldn't have forced her to. Make the cupcakes by all means, but just don't go. Still that would have negated the point of the book - so maybe it just needed handling/writing a little bit so it didn't feel like Mel's friends were bullying her into doing something she didn't want to do.
But once the actual mystery got going, it was fun.