The storyline and plot is PERFECT for a time travel concept UNLIKE ALICE cough* cough* . The main characters are actually SMART and they actually come up with realistic good plans to try and solve the mystery. The antagonist are all so intelligent that they use MANIPULATION rather than brute force to get what they want. SIGNAL + WORLD OF THE MARRIED = KAIROS

The present and the past are easily distinguished and they put DATE LABELS ON EVERY TRANSITION that makes it easier for the viewers to differenciate. It has ALMOST 0 PLOT HOLES and every change in the past perfectly resembles the change in the future flawlessly. The story IS NOT DRAGGY and every episode ends on a cliff hanger making you want more.

Recommended to VETERAN KDRAMA VIEWERS who can appreciate MYSTERY THRILLERS with NO ROMANCE