The Prisoner in the Castle

Maggie is a brave, educated, strong young woman who I have come to love through the series. The ending of The Paris Spy was an unexpected cliffhanger and I was eagerly waiting for this installment, but unfortunately this was a disappointment.
Nothing really happens on the Island of Scarra where all these agents are isolated and imprisoned. They start getting killed off one by one but and I thought Maggie would get an opportunity to investigate and find the killer, but that's not what happened. Whatever she learned, she just stumbled upon by accident. I hoped atleast the story arc of the German Spy would be interesting, but it turned out to be quite anticlimactic. None of my favorite characters seemed to have much to do here.
I would still probably continue this series because Maggie is a wonderful character but this book was definitely forgettable.