Sadly, it was just a boring slog of a read, literally the whole book is the main character whining about his wife dying while traveling to a recently discovered hole made by aliens. There are also two over-the-top characters who constantly argue with each other about religion. And one character who's kinda just there. All of them are also scientists who make so many stupid decisions that leave all of them either crippled or dead.

In the end the main character reaches the hole, looks over the edge, sees nothing and decides to go back. That's it, that's the grand conclusion.

It's not that I don't get what the book was trying to say and that it was pretty much just a metaphor for overcoming loss of your loved ones, it's that it sucked.

You can replace literally any part of the story with anything else and the story doesn't change - drop all sci-fi elements, replace the hole with any other object/place that's far away in a hard-to-reach terrain, replace really whatever you want with something else and it's still the same story.

Overall, this could have been interesting if it was about 50 pages long and if it didn't claim it was in any way related to the first book.