In Armentrout's (The Darkest Star, 2018, etc.) first YA sci-fi romance novel in a series, the boy next door is super-attractive, insufferable, and a space alienand he has enemies. After Katy Swartz's father died three years ago, she and her mother moved from Gainesville, Florida, to tiny Ketterman, West Virginia. Katy's senior year of high school is about to begin, and her mom suggests that she say hello to her teenage neighbors, a brother and sister named Daemon and Dee Black. Although Katy, who's now 17, would rather be reading or writing her blog, she remembers her father's advice: "Come on, Kittycat, don't be a bystander." Two things quickly become apparent about Daemon, though: "He was probably the hottest guy I'd ever seen in real life, and he was a total douche." However, Dee is eager to be friends with Katy, and she explains Daemon's rudeness as a product of his overprotectiveness. Something is strange, though, about the town of Ketterman, including reports of "people-shaped things of light." The amazing truth is that the Blacks, and other local residents, are aliens, and they have extraterrestrial adversaries who are out to destroy them. However, no matter how much Daemon tries to keep Katy out of the fight, she remains determined not to be a bystander. Armentrout employs some fairly standard genre tropes, such as an obviously very attractive female protagonist who refuses to believe that she is, and a love interest who's a specimen of over-the-top physical perfection. The couple's love-hate romance dynamic is nothing new, either, although many readers will enjoy how the relationship builds and enjoy some steamy scenes. Armentrout's writing is solid, and she provides Katy with a believable voice. A few sly references indicate that the author is quite aware of her genre's conventions: "You've been an angst-ridden teenage girl, like the kind in the books I read"; "You don't sparkle, do you?" The story is well-paced throughout, and the sci-fi elements provide some freshness, setting groundwork for future installments. (Bonus chapters, told from Daemon's point of view, are also included.)A page-turner for genre fans, despite few real surprises. Copyright Kirkus Reviews, used with permission.