Grayson Ames and the Old Hunger

Grayson has trained Edith and now she's ready to strike out on her own. But everything positive in Grayson's life has to be followed by a heap of negative. His 18th birthday, another murder in Progress, and worst of all, the memory. Memories he's kept forgotten for eight years are now back to haunt him, sometimes literally.
 
The third installment in the Grayson Ames, PHD series, this book may answer the question that Grayson has been searching for: Who killed his old partner, Patrick Denton?