This book reminded me of Life after Life. I don’t know if Claire North was inspired by Kate Atkinson, or it was the other way around. Both books were excellent, this one being a thriller.
Life after Life was about reincarnation. Supposedly, if you tried, you will become better the next reincarnation. With enough cycles, your will find nirvana eventually. This book is more like Groundhog Day, at the duration of life-time. Those kalachakra (Sanskrit for “time wheel”), or ouroborans (Greek myth of a snake eating its own tail), would re-live their lives, with full memories of all the previous ones, forever. Harry August, one of them, was also a mnemonic. He remembered all his previous lives, perfectly.
There were some clever innovations. Kalachakras can communicate to past and future generations. Leave a time-capsule and the future generation will get your message. To communicate backward, an infant will tell a dying one. When the old was reborn, he or she would have essentially travelled back in time. Repeat this process and you can effectively communicate backward for several hundreds of years.
Kalachakras tended to do well financially, they invested or gambled with prescience. They were also highly skilled with centuries of education and practices.
The central theme of the book was the ethics of interfering future, or temporal events. Should one change the future if capable of? Is it ethical to kill before the crime? Would you kill Hilter’s parents so that he wouldn’t be born?
Harry August was conflicted. He would proactively kill a murderer, before the actual murder. Yet he spent centuries trying to prevent the antagonist who tried to influence future in a larger scale.
One of them committed suicide by Forgetting. That’s an interesting concept that after some cycles, the world became unbearably boring. To Forget is to wipe their own memory clean so that they would experience again. Immortality is really a curse, particularly for those who cannot die.