Astin will play the then-police commissioner of New York City in the upcoming drama.

Sean Astin has some very big shoes to fill.

The Lord of the Rings alum is set to play Theodore Roosevelt in TNT's forthcoming drama series, The Alienist. Astin will play the famed historical figure before his presidency, when he was police commissioner of New York City.

Based on the best-selling novel of the same name by Caleb Carr, the psychological thriller is set in the Gilded Age of New York City in 1896, a time of vast wealth, extreme poverty and technological innovation. The drama follows a series of haunting, gruesome murders of boy prostitutes that grips the city, at which time Roosevelt calls upon criminal psychologist (also known as alienist) Dr. Laszlo Kreizler (Daniel Bruhl) and newspaper illustrator John Moore (Luke Evans) to conduct a secret investigation.

Astin's Roosevelt is described as a brilliant, ambitious but principled reformist determined to clear up corruption in the police force he heads. While usually inured to crime in New York, Roosevelt becomes outraged over children being murdered in his city and develops a warlike zeal to find the perpetrator.

Astin joins a cast that includes Dakota Fanning, Robert Wisdom, Q'orianka Kilcher, Matt Lintz, Matthew Shear and Douglas Smith.

The series adaptation hails from director Jakob Verbruggen (Black Mirror), who exec produces with Cary Fukunaga, Eric Roth, Hossein Amini and Anonymous Content's Steve Golin and Rosalie Swedlin. Paramount Television is co-producing the series with Turner's Studio T. Filming is under way in Budapest, Hungary.

Best known for films Rudy and The Goonies, Astin's TV credits also include 24, The Strain and the upcoming second season of Netflix's Stranger Things. He is repped by Abrams Artists Agency, Luber Roklin Entertainment and Bloom Hergott.

Roosevelt, who would go on to become president in 1901, has also been portrayed by Robin Williams (Night of the Museum) and Tom Berenger (TNT's Rough Riders) in popular culture.