A Cold Case 24 Years Buried: Park Seo Joon, Park Hae Il, and Choi Dae Hoon Join Forces for New Period Mystery Firefly

Three of Korea’s most compelling actors are teaming up for a film that digs into one of the country’s most turbulent decades. Park Seo Joon, Park Hae Il, and Choi Dae Hoon have officially been confirmed to lead “Firefly” (working title), with filming set to begin September 27.

The production companies made the announcement on August 21, and the premise alone is enough to raise eyebrows: a mystery that jumps between 1974, under South Korea’s military dictatorship, and the summer of 1950, right after the Korean War broke out — all built around a secret that’s stayed buried in Hwayong Village for 24 years.

Who’s Playing Who

Park Seo Joon takes on Joon Kyung, a detective whose career has stalled thanks to guilt by association. Desperate for a breakthrough, he takes the bait offered by a mysterious figure and gets pulled deeper into Hwayong’s dark past.

Park Hae Il plays that very figure — Man Seop, the man who lures Joon Kyung to the village with the promise of career-boosting results, setting the entire mystery in motion.

Choi Dae Hoon rounds out the trio as Tae Sik, a deputy director at the Korean Central Intelligence Agency who genuinely believes his every action is patriotic — a chilling character type for a story steeped in Cold War-era paranoia.

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Park Seo Joon show: Overview

The Director Behind It

Helming the project is Lee Joon Ik, the acclaimed filmmaker behind King and the Clown, Dongju: The Portrait of a Poet, and The Book of Fish — known for turning weighty historical material into deeply human stories. That track record makes “Firefly” one of the more anticipated Korean productions heading into the back half of 2026.

Park Seo Joon, meanwhile, remains busy on the small screen too, currently starring in the variety show “Unplanned Trip: Limited Edition.”

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