Choi Jin Hyuk went from his role as Lee Min Ho's older colder brother in "The Heirs" to playing an intern working with his ex wife in "Emergency Couple." But the actor has already made acting plans for after his "Emergency Couple" character woos back his ex wife and finally stands up to his fictional mother.

Next he will play the role of a young police detective, Lee Joon Hyuk, in the tvN comedy "Flower Grandpa Investigation Unit." The character is a genius detective who graduated with honors from the police academy. Despite his impressive IQ, he encounters a mystery he cannot solve when he suddenly ages and turns into a 70-something grandfather. Veteran actor Lee Soon Jae will play Choi Jin Hyuk's character as a grandfather. The actors has been in dozens of dramas including most recently appearing in "Potato Star 2013 QR3," "Ugly Alert," "Childless Comfort," and "Horse Doctor."

Fortunately, Choi Jin Hyuk's character is not alone in his sudden aging. He is one of three detectives who become grandfathers and form the Flower Grandpa Investigation Unit. And none of them have a clue as to why it happened.

One of the other detectives will be played by Park Min Woo, who appeared in "Flower Boy Ramen Shop," "Scandal: A Shocking and Wrongful Incident" and also appears in "Can We Love?" He portrays the younger version of the grandpa played by Byun Hee Bong, who last was seen in "Ohlala Spouses" and "My Girlfriend is a Gumiho."

Park Doo Shik, who currently plays Choi Jin Hyuk's ex-brother-in-law in "Emergency Couple," will play the younger version of the detective/grandpa played by Jang Kwang. Park Doo Shik also played Lee Jong Suk's classmate in "I Hear Your Voice." Actor Jang Kwang was last seen in "Goddess of Fire: Jeonji."

Super Junior's Heechul has been cast as the detective who helps the grandpas recover their lost youth. Actress Park Eun Ji, who was in "Standby," has been cast as Choi Jin Hyuk's fiancée. She will probably not be too pleased by his transformation into a senior citizen. And to add more fun to the plot, there may be more body swapping.

Choi Jin Hyuk may have taken the role in preparation for his upcoming enlistment as a conscripted police officer in the Seoul Police Promotional Unit. Although he has no set date for his enlistment, it's never too soon to pick up some good detective skills.

The 12-episode "Flower Grandpa Investigation Unit" begins on April 30.