The Alienist by Caleb Carr

It is 1896. The city is New York. Journalist John Schuyler Moore is brought by his companion Dr. Laszlo Kreizler — a clinician, or “alienist” — to see the horrendously damaged body of a juvenile kid deserted on the incomplete Williamsburg Scaffold. From that point the two set out on a progressive exertion in criminal science: making a mental profile of the culprit in light of the subtleties of his violations. Their perilous mission brings them into the tormented past and bent psyche of a killer who will kill in the future before their chase is finished.

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