This was another really good book in this series. Both had appearances in the previous books. Holly is an elemental (human with fae heritage) and controls metal. She's an inventor for the SOS. Will is a sanguis demon (think vampire). In the previous book, both were kidnapped. Holly for her abilities and intelligence, Will as an experiment. Will was given a platinum heart and is now after Holly. I liked the twists and turns. I liked seeing Adam (the founder of the GIM) and look forward to his story which is next. The last book features Holly's "cousin" Sin (St John)- Daisy, Miranda, and Poppy's brother. I read this for Romance-opoly Coffee Shop I'm also using this for Ripped Bodice Summer Bingo violet eyes square (Queen Mab).