Switching identities can have comic consequences, but it can also save lives. That's the premise of "Key of Life," the film that stars Lee Joon, Yoo Hae Jin, Lim Ji Yeon and Jo Yoon Hee.

In "Key of Life" Lee Joon plays a washed-up actor, who is ready to end it all when he sees the chance to change places with a cold-blooded contract killer. But before he plans to kill himself, he decides to visit a sauna.

Yoo Hae Jin, last seen in the hit film "Veteran," "Tazza: The Hidden Card" and "Pirates," plays a contract killer named Hyung Wook. He is on his way to kill someone but decides to stop at the sauna. After an accident he loses his memory.

The film is based on a Japanese film of the same name written by Kenji Uchida and the Korean version promises to be very similar. When Lee Joon's character witnesses Hyung Wook's accident and amnesia, he sees a chance to start anew. He steals Hyung Wook's identity, only to discover that he is impersonating a killer and must interact with dangerous gangsters. The gangster thinks he is a failed actor and is miserable. Fortunately, the gangster gets his memory back and both men are better for having seen the world from a different point of view. The actor, having had the experience of living in another man's shoes, becomes a better actor and finally achieves success.

The switch is also good news for Eun Joo, the person that Hyung Wook was on his way to kill. Lim Ji Yeon, who recently appeared in the comedy "High Society" and won three Rookie Awards for the film "Obsession," plays Eun Joo.

Rounding out the cast is Jo Yoon Hee, who plays the emergency medical attendant Rina. Jo Yoon Hee is best known for her roles in the dramas "My Husband Got A Family" and "Nine: Nine Time Travels." Last year she starred in the film "The Con Artists" with Lee Hyun Woo and Kim Woo Bin. This year she can also be seen in the film "The Joseon Magician," starring Yoo Seung Ho and Go Ara.

It's the second time Lee Joon has played an actor. His role in the film "Rough Play," aka "An Actor Is An Actor," was that of a superstar who hit rock bottom. After that the actor played a teen father in "Heard It Through The Grapevine" and a psychotic barista in "Gap Dong."

The actors have been filming since the beginning of August and according to Yoo Hae Jin, all is going well.

"Everything went well thanks to the preparations," said Yoo in an interview with the media outlet Newspim. "I am going to do my best to make this movie work."

The film will be released in 2016.