The story follows Roosevelt, then New York City police commissioner, and Dr. Laszlo Kreizler, as their investigative team attempts to solve gruesome murders through new methods including fingerprinting and psychology.

The film studio has since moved the rights over to its television division, where a 10-part event TV series adaptation began its run on January 22, 2018, on TNT.

Booklist described it as "superbly atmospheric and compelling",[4] Forbes called the work a "fascinating, fast-paced spine-tingler",[5] and author Paul Levine wrote in the Chicago Tribune "at the end the reader thirsts for another tale of Dr. Laszlo Kreizler".

[6] The Houston Chronicle characterized it "an out-and-out page-turner",[7] and The Seattle Times noted "Carr brings the dual sensibilities of historian and novelist to the story.

"[8] Narrated from the first-person perspective of John Moore, a crime reporter for The New York Times, the novel begins on January 8, 1919, the day that Theodore Roosevelt is buried.

Kreizler is surrounded by those he has rescued, including his black servant, Cyrus Montrose, and a boy named Stevie "Stevepipe" Taggert.

Together, they reminisce about their times with Roosevelt, but they focus on one moment: the spring of 1896 and their efforts to catch a serial killer on the Lower East Side of Manhattan.

Though makeup paint and powder on his face are still intact, his eyes are gouged out, his right hand is chopped off, his genitals are cut off and stuffed between his jaws, he has huge gashes across his entire body, his throat has been slashed, and his buttocks are "shorn off".

Kreizler asks for some young detectives who are open to new methods and receives the help of Marcus and Lucius Isaacson, two Jewish brothers who were hired when Roosevelt began removing corrupt police officers from the force.

The Isaacsons bring sophisticated methods, such as the Bertillon system and fingerprinting, to the investigation, although these were not popular in New York City police departments at the time nor accepted in courts of law.

Kreizler, Roosevelt, Moore, and detective Sara Howard must deal with various interest groups during their investigation who wish to maintain society's status quo, including a corrupt police force, which takes bribes from owners of the brothels whose prostitutes include poor immigrants; the Catholic Church, which is wary of the potential power of an organized immigrant population; the Episcopal Church; and J. P. Morgan.

[6] It is set in 1896, "the moment in history when the modern idea of the serial killer became available", eight years after the Jack the Ripper case, and at a time when the word "psychopath" was new to scientists.

[6] Historical figures such as Lincoln Steffens, Jacob Riis, Anthony Comstock, and J. Pierpont Morgan appear briefly in the novel and interact with the fictional characters.

[13] Carr includes period details, such as descriptions of "sumptuous meals of turtle soup au clair, Creole eggs, broiled squab, saddle of lamb a la Colbert and 'a liter of smooth, dark Wurzburger (beer) that had a head as thick as whipped cream'".

[14] Carr, a historian by training, wanted to find a form of writing where he could meld his interest in fiction with his knowledge of history.

The book has received generally favorable reviews; "while most critics found it entertaining, some said it was sometimes flabby with historical detail and its prose was less than literature.

"[11] In a review published in Booklist, Brad Hooper calls The Alienist and Caleb Carr's sequel, The Angel of Darkness, "superbly atmospheric and compelling".

"[5] Writing for The Record, Laurence Chollet notes: "The story feels like a Sherlock Holmes tale, reads like a modern thriller, and is historically accurate.

"[14] In his review in The Gazette of Colorado Springs, Victor Greto wrote: "Through his research into the New York of the late 19th century, [Carr] has also fleshed out an atmosphere and a time that, on the one hand, seems grimly real and unapproachably evil, but, on the other, is within our intellectual grasp.

"[20] In his review of the book for the Chicago Tribune, Mortal Sin author Paul Levine writes: "the long story never becomes tedious, and at the end the reader thirsts for another tale of Dr. Lazlo Kreizler".

[7] Christopher Lehmann-Haupt writes in The Tampa Tribune: "Carr has lovingly evoked not only a physical sense of old New York but the spirit of the time as well, when the powers in charge were worried about unrest among the masses of cheap immigrant labor.

"[21] In a review for The Seattle Times, Deloris Tarzan Ament comments: "A contributing editor to Military History Quarterly, Carr brings the dual sensibilities of historian and novelist to the story.

"[8] In his review for The Washington Post, novelist Jack Katzenbach argued that Carr's impeccable research and rich detail hindered the work's pace but rewarded readers by portraying "the excitement of a world on the verge of change, where invention was the stuff of daily miracle," specifically when it came to forensics.

And his detective team anticipates the feminist movement by enlisting a tough-minded career woman who's unafraid to pack a pistol and spout a bit of scatological English.

[8][25] In January 1995, The River Wild director Curtis Hanson was reported to have been in the process of final negotiations with Scott Rudin and Paramount Pictures to direct The Alienist.