It's a strange feeling to realise you've never reviewed the drama that is one of the best ever made and one of your personal favourites as well.

Circle is a rare Korean science fiction drama; a mind-bending, time-warping tale with the first half of each episode set in 2017 and the second half 20 years in the future. Events unfold simultaneously in both timelines, with 2017 and 2037 being inextricably intertwined.

Future cop Kim Joon-hyuk (Kim Kang-woo) in 2037 tries to uncover the mystery of what happened to a set of twins Kim Woo-jin (Yeo Jin-goo) and Kim Bum-gyun (An Woo-yeon) back in 2017, while in that time we see the two young men embark on their own investigation around the mystery of Han Jung-yeon (Gong Seung-yeon), whom Bum-gyun is convinced is an alien.

At a tight 12 episodes, the show wastes little time on filler and instead launches itself into action from frame one. It's a thrilling ride that barely allows you to draw breath in either time period as it races to a fascinating and at times unexpected conclusion.

The future envisaged by Circle includes memory-altering technology and the show's constant questioning of how our memories shape who we are is endlessly insightful and often poignant. The ambiguity the show retains even as it answers our questions is its best quality and it's that ambiguity that has led to hopes the show would have a second season.

Circle is a rare beast from Korea and its almost-universal acclaim may make it possible for the country to start producing more hard science fiction. We can only hope that happens soon.