Focusing on John Brown's attack on American slavery, the series was created and executive produced by Ethan Hawke and Mark Richard.

[5] The series is told from the point of view of Henry "Onion" Shackleford (Joshua Caleb Johnson), a fictional enslaved boy, who is part of John Brown's (Ethan Hawke) motley crew of abolitionist soldiers during the time of Bleeding Kansas, eventually participating in the famous 1859 raid on the Federal Armory at Harpers Ferry, Virginia (since 1863, West Virginia).

Author James McBride was involved in the production and according to him, "John Brown is a real hero to me and to many Black people who are no longer alive.

[19][20] Albert Hughes, Kevin Hooks, Darnell Martin, and Haifaa al-Mansour, Michael Nankin, and Kate Woods each directed an episode.

[22][23][24] In July 2019, Joshua Caleb Johnson and Rafael Casal joined the cast as Henry "Onion" Shackleford and John Cook.