In the final book in the Perfect Chemistry series, the youngest Fuentes brother Luis takes center stage. Older brothers Alex and Carlos have overcome obstacles with high school, relationships, and trying to stay out of the Latino Bloods and they have always been protective of Luis. Luis has managed to stay out of trouble and out of gangs so far. He’s a math whiz and an accomplished swimmer, although he does push his luck by being quite a thrill seeker. He’s now living back in Southside and meets Nikki Cruz, a doctors’ daughter who has been burned by a previous relationship. She’s not too eager to take a chance on someone like Luis who on the surface seems so similar to her last rotten boyfriend. Luis wants to earn Nikki’s trust, but he is pulled in another dangerous direction that could change his life forever.This book follows a similar formula to the last two books, but with a couple of added surprises. Luis starts off with such high ambitions and his been successful with school, and aspires to be an astronaut one day. He is as likable and charming as his brothers, and I was rooting for him to succeed and stay on the right path. It took me a little longer to warm up to Nikki. She is so guarded it is hard to get to know her. However, I liked that she is a dog lover and volunteers at an animal shelter. Their relationship is as hot and intense as you might expect from the previous books.My favorite parts of Chain Reaction featured Luis with his brothers Alex and Carlos, who make several appearances. It’s great to see how their lives have progressed and the devotion they have to their families. Their antics livened up the book when things started to get heavy. I was surprised by the twist in the book, and the after effects. There’s never a dull moment for this family.Maybe the novelty wore off a little bit with this one, but I think I preferred the first two books in the series. I enjoyed Luis’s story and was satisfied with the conclusion overall, but it was missing that certain something that made the first books special. Although it’s not my favorite book in the series, I’m glad I read it. The excitement and tension in the book had me flying through the pages. I think fans of the series will find it enjoyable and like the closure it provides.