The fellow members of MBLAQ saw the poster for Lee Joon's upcoming tvN drama "Gapdong" and thought he looked like a mental patient on it.

"They really liked it," he said.

His character in "Gapdong" is Ryu Tae Ho, a smart young barista who idolizes a serial killer. THe is one of five characters who have different reactions to the return of a killer, who disappeared 20 years ago. People assumed that the killer died and suddenly he is back committing new crimes. Or is he? Could the new crimes be the work of a copycat killer.?

Ryu Tae Ho's reaction to the return of the serial killer is suitably creepy. In the teaser trailers for the drama he says, "My hero, you were alive."

It's chilling.

Lee Joon was last seen in "Rough Play," where he portrayed an actor who achieves fame and then discovers the dark side of success. The young actor created some controversy with the explicit bed scenes filmed for that movie.

When asked about the controversial scenes in his last film, the actor said "I had no objections because it was a necessary part of the movie. Besides, it's acting, not real life."

And while he is still acting and does not worship serial killers in real life, his Gapdong character may also spark some controversy.

But every character in this drama is intense.

Yoon Sang Hyun, who last played a defense attorney in "I Hear Your Voice" will play Ha Moo Yeom, a police officer with a personal grudge against the killer. He wants to find the killer to clear the name of his wrongly accused father. His father killed himself rather than continue to be harassed by the police over a crime he did not commit. Ha Moo Yeom is sure the crime was committed by the serial killer. So, he is grateful the killer is alive.

The killer may have returned because the statute of limitations on his crimes has expired.

Sung Dong Il plays Yang Chul Gon, the policeman who originally let the killer get away. He greets his return with renewed dedication. This time he will find him.

Kim Min Jung is Mariah Oh, a psychiatrist with an alter ego. During the day she looks and acts like a respectable doctor. At night she is glamorous and mysterious. The news of the killer's return fills her heart with fear.

Kim Min Jung said that she could not fall asleep after reading the script.

Kim Ji Won plays Ma Ji Wool, a teenager who draws cartoons. She not only becomes the killer's next prey but her cartoons may lead to the detectives solving the case.

The drama begins April 11.