*SPOILERS for books 1-3*As Alien Proliferation opens, Katherine "Kitty" Katt (now Martini) is nearing the end of her pregnancy, and she's miserable: bed rest, inability to decide on even the smallest baby supplies, and discomfort all combine to make Kitty one cranky agent.Then, a phone call comes in - Kitty's best friend from college is in trouble. Jeff and Christopher rush out to save the day, but of course it's not that easy: more problems are uncovered than are solved, and then suddenly - there's a baby on the way! Take a (half) alien baby, add the fact that dad had been force-fed untested alien drugs before conception, and you have a white-knuckle delivery on your hands.From there, things just keep going crazy and Kitty and Jeff's new-parent bliss is clouded by disappearing agents and the realization there's a mole trying to take out the team. What comes next is a lot of action, secret agent stealth, sci-fi conspiracy, and a ton of fun.My thoughts: I have been a huge fan of Gini Koch since the first book and Alien Proliferation has everything I've come to love about this series: Smart, funny dialogue, diverse and interesting characters, and boatloads of action.In addition to the sweet and sexy rapport between Kitty and Jeff, one thing I really liked about Alien Proliferation is that we get to see more of Kitty's relationships with her two BFFs: Chuckie and Reader. I have adored Chuckie since we met him (even before, kind of), and he gets one of the sweetest, saddest lines I've ever read:He got up, and I handed Jamie to him. He held her well. "She really looks like you. Beautiful baby.""I still don't see it, but I'll take the compliment for both of us."He held her for a few minutes, walked around the room with her. He finally handed her back to me. "Thank you.""For what?"Chuckie kissed the top of my head. "For letting me pretend."~page 126, Alien ProiferationSooo sweet, right? We (and Kitty) also learn a bit more about Chuckie through some of the other characters he works with. I was very pleased with the amount of information/page time Chuckie had in this book.The Kitty/Reader relationship is, as always, wow. We were treated to more information about Kitty and Reader's relationship in the previous book, Alien in the Family, but Alien Proliferation gives us more insight from Kitty's POV, and it was moving.And....Christopher gets a love interest in this book - I know, right?!? He's such a great character and he's had a few hard knocks so I was especially pleased to see him happy. I'm looking forward to seeing them together in future books, giving Jeff and Kitty a run for their money in the "happy and sex-crazed" department.My issues with this book were really specific to me personally: I had a hard time following some of the conspiracy plot, and Kitty referred to her boobs as "torpedoes" way too much; we get it - they're huge. (and I may have been jealous of Kitty's post-birth recovery; you'll have to read to find out why, lol)This series is often described as "over the top" which is exactly right - but it's so much fun!! Gini Koch's Alien series holds a proud place on my "Keeper" shelf and Alien Diplomacy is already on my "Books I Can't Wait For" list.My rating: 4 1/2 stars!