I seeked out and watched this series on the strength of the name of director Oriol Paulo, all of whose movies I have loved so far, but I discovered a new name in the process: writer Harlan Coben. Don't get me wrong, Paulo (who also collaborated on the adaptation of Coben's book) proves again that he is a master at controlling the tempo and raising the tension. But it's Coben's puzzlelike, multilayered plot structure, where every piece slowly falls into place until you get the full picture, that is the chief virtue of this series. Not to overlook the excellent cast - really the cream of the Spanish crop in actors working regularly in this genre (Aura Garrido, in particular, is sooooooo good that you don't see the actress - only the character(s)). I have only three reservations about this series: 1) in episode 5, the violence against women is ugly. I get its dramatic purpose, but it's still hard to watch. 2) shouldn't Olivia's daughter be a little younger? 3) the finale doesn't really have the mind-blowing twist that you might expect from an Oriol Paulo project; the biggest twists & revelations occur in earlier episodes. Still, I would highly recommend this series to Oriol Paulo fans as well as to anyone who loves puzzles. I rated every episode 8/10, so 8/10 for the show as a whole.