My daughter recommended this to me as it involves puzzles.
I reluctantly decided to watch, but I was hooked from the first episode!
I could see aspects of myself in the main character played by David Mitchell; tinnitus when he gets anxious, uneasy in social situations and of course the puzzles.
Some negative reviews cite the fact that he couldn’t replace his ‘normal’ brother at the police station, but I think it added to the mystery of whether the seniors knew something was not right. The back story of the Sinclair case added to this premise.
Highly recommended!