Hey there! I haven't read the novels yet but I have one of them on my reading pile. It is my understanding that this series is more based on the novels rather than retelling them beat for beat.

According to a quote by the author, he says:

"The book and the series are different but they do absolutely exist in the same imaginative universe. So Villanelle and Eve have many, many adventures and some of them are in the novels and some of them are on TV, and that’s sort of how I see it all."

So it looks like the books and the show are in the same universe but cover different things. Hopefully this helps!

Go ahead and read. They're very very VERY different than the show - it's not a dramatization of the novels.

If you're looking for the Villanelle we know, who is NOT a psychopath and has a heart and feelings, you'll be deeply disappointed, though. Villanelle in the novels is basically Dexter without the sense of humor.