This is an excellent crime-solving drama but it is not for the faint of heart. The crime scenes are pretty graphic and disturbing. The great tension throughout the entire drama is the pursuit of catching a very elusive psychotic serial killer who only preys on young women but always seems to be one step ahead of law enforcement. The writers were clever by shrouding the real crime engine in an envelope of mystery, by surprising the audience with the capture of someone who was caught in the act of trying to kill a young woman and who fits the profile, but his capture did not stop the murdering campaign. The sci-fi aspect of this drama adds real intrigue to the story but the real "WOW" element was the slow reveal of how the main four characters (I am including Jo Hee Bong as a main character) were unknowingly connected to each other in the past but their connection is revealed in this surreal future where most of the drama takes place.
Choi Jin Hyuk, Yoon Hyun Min, Lee Yoo Young and Jo Hee Bong turned in stellar performances. The back and forth bickering and love-hate relationship between Jin Hyuk's character and Hyun Min's character were at times priceless and comedic. Lee Yoo Young was portrayed as a brilliant professor and criminal profiler but was a contrasting character in relation to the other main characters. She was dark and caliginous---cloaked in a very unkindly past which spurned her to want to study serial killers. Her quest for understanding the mind of a killer was really a deep cry from within her soul to solve her own past and hurts. The writers did a nice job in using the character of Park Kwang Ho to not only be the lead in catching the serial killer but to be the missing puzzle piece in healing the hurts of Kim Sun Jae and Shin Jae Yi. The healing aspect of this story was a nice counter-balance to the horror and intensity of trying to find a serial killer.
"Tunnel" is certainly an entertaining drama and one that will keep you a bit nervous through many of the episodes as the good guys get closer and closer to capturing the serial killer who hides in broad daylight.