To be really clear: this isn't a prologue to The Expanse series or canonical in any way, but some of the stories in the collection feel like you're reading a conceptual draft with elements that are later developed in the series (I won't get specific so as to avoid spoilers). The stories are a mix of sci-fi/fantasy/horror. I'm rather surprised to have seen so little discussion of this story collection online, especially considering the title (Leviathan, you say?!).

Context: I got my own copy a few months ago, went to get one for a friend recently, noticed the price trending up, so I figured I'd share this suggestion before they're either gone entirely or just absurdly overpriced.

Update: Yikes! I don't know if it was my doing or not, but all of the under-$100 copies seem to be gone from Amazon since I posted this. Looks like there are still some on eBay. Might check other sites (or the library)!