Once regarded as something that happens exclusively in Guy Ritchie films and on Gypsy sites, bare-knuckle boxing is fast becoming a thriving scene in the UK—the ultimate British bloodsport.

When Clive Martin embeds with the bare-knuckle boxing elite, what he discovers is not dissimilar to Fight Club: IT technicians, builders, lifestyle coaches, and even a lawyer, all throwing their unprotected fists into one another’s faces. It’s a subculture of honor, pride, and violence.

As the UK prepares to play host to the first US-vs.-UK bare-knuckle title fight in 150 years—the biggest event the scene has known since it went underground in the 19th century—Clive tries to find out whether violence is a cause or effect for these angry young men.