Archangel

Guardian First Class Michael Sorenson joins Division 7, a secret R&D unit racing to develop a weapon capable of killing Spectres — invisible alien enemies — at scale. Fortune keeps the pace high and the mystery of a saboteur within the facility adds genuine thriller tension to the military action. Teen-age protagonists give the series broad crossover appeal without softening the stakes. The book builds directly on the events of Nova, and readers who skip the first novel will find themselves missing essential context; Archangel does not stand alone. Some reviewers found the world-building secondary to the action, which is fair — Fortune's strength is momentum rather than depth. Within its lane, though, this is confident, fast-paced military science fiction with enough character work to keep the action sequences meaningful. A solid second entry in an award-shortlisted series.