Chloë Grace Moretz is a plucky teen outwitting extraterrestrials in this sci-fi thriller based on Rick Yancey’s eponymous novel. Unfortunately the premise holds more excitement than its execution, which amounts to a lazy patchwork of themes from various young-adult dystopian franchises. Separated from her family during a series of coordinated alien attacks, Moretz’s character goes on the run to save her kid brother (Zackary Arthur) and eventually confront “the Others” with the help of a sensitive hunk (Alex Roe) and an army of child soldiers who look as if they’ve been recruited from the set of Divergent. Director J. Blakeson injects some suspense into the edgier first half, but the potential for this adolescent Independence Day to transcend mediocrity is ultimately squashed by a silly and generic love triangle that makes The Hunger Games look like Casablanca. With Maria Bello and Liev Schrieber.