This is a K-drama done right, at his best.
Everything, from the script, the cast, and the way the show was directed was bordeline perfect. I can't say this show will please everyone - well it probably won't since it's mostly a suspense/detective investigation of sort - but as for what the show was aiming for, this drama close the deal and provides the viewers with a brillant, modern filming and scenario, (mostly) avoiding the useless and the usual fancy stuff. Which is already brillant in its own way (and I don't care if I'm repeating myself).
Well, here you have it : I'm not going to explain myself why this is a very good drama, since I'm quite confident that watching it will give you a lot to think about it, and besides, people here with a much better prose than your servitor have already work to give you enough reasons to jump on the show and appreciate it with your own open mind, so you can stop reading this review now, and enjoy watching "Stranger" right now.
ASAP. Lucky you.