"Cooties" has all the makings of a new cult classic—an excellent ensemble, cheerfully acerbic dialogue, a mix of limb-ripping horror and on-point satire—save for one crucial element: a satisfying conclusion. The film, directed by Jonathan Milott & Cary Murnion and written by Leigh Whannell (2015's "Insidious: Chapter 3") & Ian Brennan (TV's "Glee"), sells the setup and keeps the tongue-in-cheek absurdity buzzing along, but botches the landing. The reluctance to place the core group of protagonists in palpable danger stifles the story's would-be imminent threat, even as the bleak anticlimactic ending resolves nothing and stops the fun dead in its tracks. In bringing "Cooties" to the screen, the filmmakers have misjudged their tone and their narrative blueprint, concocting a shoddy denouement not nearly ready to go before the camera.

Aspiring horror author Clint Hadson (Elijah Wood) has picked the wrong day to begin a substitute teaching position at Illinois' Fort Chicken Elementary. Spurred by tainted chicken nuggets, a highly contagious viral outbreak quickly spreads throughout the pre-adolescent population, turning the largely insufferable youngsters into crazed, super-strengthed cannibals. Trapped inside the school, the staff—among them, Clint's childhood crush Lucy McCormick (Alison Pill); her ridiculous hot-shot boyfriend, P.E. instructor Wade Johnson (Rainn Wilson); in-the-closet art teacher Tracy (Jack McBrayer), and rape-whistle-touting conservative Rebekkah (Nasim Pedrad)—plan to wait it out until the parents arrive to pick up their kids. When that plan quickly goes awry, they have no choice but to fend off the murderous tykes themselves.

The banter between the colorful assortment of adult characters is where "Cooties" gets most of its facetious spunk. Backed by Kreng's darkly whimsical, Danny Elfmanesque music score, the film's vibe resembles a cross between "Parks and Recreation" and 2004's "Dawn of the Dead" remake. Elijah Wood (2014's "Grand Piano") and Alison Pill (2014's "Snowpiercer") are appealing as nice-guy Clint and sweet-yet-fiery Lucy, which makes their romantic subplot especially dissatisfying when the script aloofly forgets about their relationship by the third act. Even more disheartening is the messy, convoluted non-ending, pointlessly resurrecting a character thought dead for a deus ex machine conclusion that achieves nothing in the long run and puts a damper on the film's droll, go-for-broke mood. "Cooties" fires from all cylinders early on, a jovially scathing mockery targeting the PC landscape of the public school system and the parentally infused entitlement of 21st-century offspring. Sadly, the screenplay paints itself into a corner as misguided as it is detrimental.