Set in the Seoul regional district of Gangnam frequently at night, a detective, a broker, and a prosecutor team up to chase after a black connection.

After relocating to a peaceful rural outpost, he finds himself drawn once more into the shady Gangnam district of Seoul when his daughter's friend named Kim Jae-hee goes missing.

Along with broker Yoon Gil-ho and prosecutor Min Seo-jin, Dong-won will reenter the world of vice, narcotics, and corruption in an attempt to unearth a plot that might bring down some of the wealthiest elite in the city.

Developed under the working title Bulk (Korean: 벌크; RR: Beolkeu), Gangnam B-Side is produced by Sanai Pictures [ko] with Plus M Entertainment and Story Rooftop.

[8] In January 2023, Jo Woo-jin and Ha Yoon-kyung were cast and confirmed to appear as lead actors for the series while Cha Eun-woo was still in discussion.