While I did enjoy most of my time reading it, the ending was deeply unsatisfying and there is a certain character that is unbearable and strangely written. I think there's a lot of interesting stuff in this book, but it's sadly held back by very strange choices in the plot.

I really don't understand why the author went with "imposter trickster god playing with humans." It was so disappointing and the weird superpower pill was even stranger. Even nothing at the top would've been better. There even could've been something like everyone has a different version of the top. Also a lot of the character deaths at the end seemed a bit far fetched. I did enjoy a lot of the book but there was a lot of parts I didn't love.

Feel conflicted about the book.
First part grabbed my attention with the setting up of the mystery but I felt like the second half really dragged and the payoff wasn't as satisfying as the build-up made it seem like it would be.

I wish more time had been spent at the end of the novel explaining the aliens/ the seeds/ the leviathans/the death and afterlife/ why the last characters killed themselves etc

I probably would not have finished it if I hadn't been hooked by the mystery. Think there were a bit too many themes to do them all justice

(religion, grief, death/loss, regret, all the science stuff, mountain-climbing, people going mad )

.  I liked the writing style and found it easy to read. Personally I didn't enjoy the extended descriptions of

people losing their minds descending into madness.

. 

A man goes missing and is eventually declared dead by his brother and niece. After many years, they discover what became of him; along with a case full of letters he had written to his niece (but never sent) during the time following his initial disappearance. The contents of the letters is astounding and they decide to publish the letters - this forms the basis for the book.

The main character, Harold, is an accomplished man, a former doctor, a scientist and something of an adventurer. He is recruited by a mysterious organisation, along with experts from other fields, to investigate an enormous mountain that has suddenly appeared in the middle of the ocean. But all is not as it seems, time runs strangely, there are ghostly apparitions, and former expedition members can seemingly tell the future.

What follows is a tense, gripping story; part psychological thriller, part speculative science fiction.
The letters reveal Harold's state of mind, the paranoia of all of the party, and the many secrets and mysteries surrounding the mountain. The style of the story means that some of the characters aren't hugely developed but, that also adds to the sense of isolation and suspicion felt by Harold.

As with all mysteries, the reveal is an important factor in overall reading satisfaction. I thought the final twists and turns were interesting but maybe not as much as the rest of the book - I felt like it either needed to be more vague or explored in more depth.

Overall, I think this is a book where the journey was more important than the destination and I enjoyed the gripping journey up this mysterious, mind-bending mountain.

Thank you to Harper Voyager for providing a netgalley review copy