More like a 4.5 stars. 
 I'll admit, I've been impressed at how the storyline has been able to progress even after the end of the bid stroy arc in Spider's Revenge, Book 5 with the death of Mab Monroe. Here we are at book 9 and I'm still just as interested, maybe even moreso, with these characters. 
 Heart of Venom deals with Sophia's past. We know that something bad happened to her and JoJo gave Gin a brief explanation, but we've never gotten the whole story. Well, when Fletcher first rescued Sophia from Harley Grimes he became the barrier between her and Grimes. With Fletcher around Sophia was safe. Fletcher has been dead for a number of months now and it was only a matter of time before Harley Grimes caught up with Sophia. What Grimes didn't take into consideration was Gin. Gin will stop at nothing to keep Grimes from hurting Sophia again. 
 I like that with each book Jennifer Estep has successfully created new bad guys for Gin to fight. She's been really creative with who / what they are, especially the elementals. Harley Grimes is a fire elemental and, along with his sister Hazel (also a fire elemental), they've been in the killing game for a number of years now. I liked the fact that Grimes' main objective was just to get Sophia. There was no ulterior motive behind her kidnapping. To me, this almost makes him more scary. He's got nothing else to lose. 
 We do get more regarding the Gin and Owen situation. I know that after the events in Widow's Web, many readers were upset, myself included, with the direction of their relationship. By Deadly Sting, I'll admit I was on the fence about where I wanted them to go. I don't want to give anything away, but just know once Jennifer Estep starts a story thread she definitely keeps up with it. 
 To me, this book feels like we are on the verge of the end of the series. I almost hope that this is the case, as sad as it will make me to see the series end. The books follow a specific formula and however much Jennifer Estep changes things up, eventually it all comes back to: bad guy in town, Gin fights them, Gin wins. I want this series to end on a high note and right now it's really good. I would hate to see it fizzle. Hopefully, everyone else involved will know the right time to say good0bye as well. 
 Until then, I look forward to continuing to read more about Gin and Co. This is definitely one of my favorite series and Heart of Venom will not disappoint.