Apology in advance: Difficult to fully summarise my issues with this without spoiling it so you'll have to forgive me if any of this sounds like it's without substance.

This story was amazing, until it wasn't. It was gripping, and I really enjoyed the twisty paths the author takes us on trying to figure out who did what, who is who, who is who in the past, who knows who already and who knows what other strange questions are unravelled throughout. Really clever, a complex unravelling that I really enjoyed.

The acting was superb, Seo In Guk - who i'd seen previously in a radically different role (goofy, light hearted etc) in Shopaholic Louie was amazing in this role as a much darker character with clear "damage". He keeps you on your toes throughout trying to work out if he's just got baggage from the past, or if he's actually missing some key parts of his humanity. Jung So Min I saw previously in Because this is my first life, and in many ways it's a similar type of character so was instantly familiar. The third main character was Park Sung Woong who I saw last in "Remember" - plays Jung So Min's older brother and police officer, always delivers a strong performance and is key in all the unravelling that goes on, his character has to resolve and handle a number of complex things in his past and how he copes with them and I really believed in his character.

I was totally hooked on this all the way through, it made a nice change from some of the lighter fluffy ones (which this most definitely is not) and has quite a lot of depth - it's not just solve one mystery and all done, there's layers upon layers.

However after the 16 episodes are done, i'm left with a feeling verging on anger and frustration at the ending. For me that's why the rewatch score is so low, otherwise this would have been a definite rewatch. The ending just seemed unnecessary, there were options going forward hinted at earlier in the story that could have been used to make a better (IMHO) ending. As I warned at the start, the area I have the most critical feedback on I can't because otherwise it's a spoiler.

All I'll say is - watch it, it's definitely worth the watch, but brace for the conclusion.

Props for some supporting characters / actors - Tak (Jang Yun Nam) provides a great sounding board for Park Sun Woong's character, and I liked that she was a strong character in her own right (though I can't imagine anyone not being strong who gets to any kind of position in the police force). Im Yoo Ri (Go Min Shi) was another interesting character to watch and I really liked the journey of improvement she went on ultimately - which is kinda why I was more let down by the ending as I was really expecting that this was the blueprint for the way forward for the final ending as well... not to mention a flash forward x years to see her "reborn" and doing well with good support around her. Ah well.