Sean Astin’s next role might require him to speak softly and carry a big stick. The Stranger Things actor is set to star as Theodore Roosevelt in TNT’s upcoming 10-episode straight-to-series psychological thriller The Alienist. The story is set during New York City’s Gilded Age, when the future Rough Rider, NY governor and U.S. president was the city’s Police Commissioner.

A co-production of Paramount Television and Turner’s Studio T, the drama is set in 1896, when a series of gruesome murders of boy prostitutes has gripped the city. Newly appointed top cop Roosevelt calls upon Dr. Laszlo Kreizler (Daniel Brühl), a criminal psychologist — aka alienist — and newspaper illustrator John Moore (Luke Evans) to conduct the investigation in secret. Joining them in the probe is Sara Howard (Dakota Fanning), a headstrong secretary at Police Headquarters. Robert Wisdom, Q’orianka Kilcher, Matt Lintz, Matthew Shear and Douglas Smith co-star.

Brilliant and ambitious yet principled, Roosevelt is a crusading reformist determined to clear up corruption in the police force he now heads. While usually inured to crime in New York, Roosevelt becomes outraged over the fact that children are being murdered in his city and develops a warlike zeal to find the perpetrator.

Jakob Verbruggen directs and exec produces along with Cary Fukunaga, Eric Roth, Hossein Amini and Anonymous Content’s Steve Golin and Rosalie Swedlin. Production is underway in Budapest.

Best known as Sam from the Lord of the Rings trilogy, Astin’s recent credits include Unleashed, The Do-Over, Stranger Things, The Strain and multiple voice roles including Raphael in the Teenage Mutant Ninja Turtles TV series and Chester in Bunnicula.

He is repped by Abrams Artists Agency, Luber Roklin Management and attorney Dave Feldman.