In this novel we meet Matthew's nemesis, Professor Fell.
I love how Matthew is growing throughout the series. At first in Speaks the Nightbird Matthew is uncertain and a bit naive. As the series continues, he is learning and becoming more and more sure of himself. As he takes part in the scarier and darker side of life,as in Mister Slaughter he becomes more hardened, more worldly. Now in his latest, Matthew is reminding me of that old Nietzsche quote: "Battle not with monsters, lest ye become a monster, and if you gaze into the abyss, the abyss gazes also into you."
Will Matthew survive this look into the abyss? You will have to read it to find out!