He was the roguish up-and-coming hotshot, bagging Best New Actor in the Golden Horse Awards 2011 for his role in You Are The Apple Of My Eye. Until a drug scandal three years later saw him fall from grace.

Now, five years on, Kai Ko is making his official return to showbiz, and not in a small way. He plays the lead role in Agent From Above, dubbed Taiwan's most expensive drama ever produced.

Based on the best-selling book series of the same name, the modern-day supernatural crime thriller sees Kai as Han Jie, who is forced to work as a heavenly agent on earth to defeat demons and solve crimes as redemption for his sins.

Armed with supernatural powers and magical weapons given by the gods, this role is also touted to be the Asian version of exorcist John Constantine. The cast list includes Sonia Sui, Kuo Chi-chien, Pipi Yao, and Wang Bo-chieh.

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Life for Kai hadn't been easy following the controversy and rumoured failed relationships, including one with heiress Lilian Chen.

Even though he worked on arthouse film The Road to Mandalay and made a cameo in Mon Mon Mon Monsters during his five-year hiatus, this is his first big project since his scandal.

During a press conference on Tuesday (Dec 10) in Taipei, the 28-year-old confessed that he was extremely grateful for the opportunity.

"This is a big physical challenge. I haven't filmed action scenes in five to six years."

He added self-deprecatingly: "Han Jie is seeking atonement after experiencing hardships, that's something I can portray quite well."

In preparation for his role, Kai has been training with martial arts choreographer Jimmy Hung (Sammo Hung's son). Not only will the drama be physically intensive for the actors involved, it also requires extensive special effects editing. In fact, even though filming for the pilot episode has already wrapped, the special effects will require at least a year of editing to complete.

Production cost for each episode is expected to be TWD30,000,000 (S$1,342,000). With six episodes planned, the first season alone is expected to exceed TWD180,000,000, making it the most expensive drama to be produced out of Taiwan.

The series is jointly produced by mm2 Entertainment Taiwan, Cai Chang International Inc, and Goodfilms Workshop.

Agent From Above is scheduled to air in 2021.

rainercheung@asiaone.com