I bought this under the impression that it was a book from which some of the source material for Half Life's storyline came. I may have misread something about it on the internet, but it is one of the three books you can find in Gordon's locker at Black Mesa.
Turns out, it's mostly about a eunuch who stalks California, castrating and murdering young homosexuals so they join his ghost retinue that he can only see at night.
There is a slightly odd preoccupation with crowbars, so there is that. As well as gratuitous amounts of gay sex. Not particularly graphic, but it's there.