Instruct: Classify a review as either positive or negative.
Query: A first-rate page-turner!

A first-rate page-turner that has something to say and that will stay with you long after you've finished reading it. As suggested by the title, the book is more than a medical thriller involving the brain. The story raises important moral and ethical issues regarding parents who would do anything to raise perfect child and medical practitioners who would oblige them for the right price. GRAY MATTER is also a terrific cop novel that will hold you in suspense to the last paragraph. The characters are engaging and complex and so well depicted.What a pleasure to read. What a pleasure to see a thriller with thought and soul and smart, stylish writing. This is an all around winner.