I hate this question.
Of course, I appreciate the asker's curiosity. There are plenty of people in my life who should care what I'm up to, but never bother asking. Even better, they may sarcastically acknowledge that I do "a little bit of writing". Even still, being asked what my book is about puts me in a state of perplexed anxiety every time.
In large part, I write to work through troubling things I have seen or experienced. I wrote Lifeless as a book because it took that many words and pages and chapters to finish what I had started. I can't summarize it for small-talk; that is a talent I sorely lack. I start with some optimism, trying to get across the general idea. The listener either wants me to give away the story, or they don't care. Either way, I'm always disappointed by the effort.
There is also a genre issue. Lifeless is historical fiction, but it has a fictional scientific element. When an acquaintance hears "sci fi," their eyes either glaze over or light up. Both responses discourage me. This book isn't the type of science fiction I think of when I go looking for a sci fi book to enjoy. To say my book is sci fi, though technically accurate, feels deceptive.
Even historical fiction, the genre I can cite with confidence, is not without issue. With shows/books like Outlander or Game of Thrones, historical fiction is now part of popular culture. But there are no dragons in Lifeless. Or bodice ripping. Sorry.
I'm sure there is a professional way to respond and my inexperience and introverted nature are combining to thwart me yet again. So I'll keep replying to the question until I find the correct short sequence of phrases that does justice to myself and my book.