Lupita Nyong'o in "Little Monsters"

It’s telling that the weapon of choice against a zombie apocalypse in “Little Monsters” isn’t a shotgun or a hatchet, though they both make an appearance in Abe Forsythe’s hilariously grizzly fourth feature, but rather the ukelele which is bound to disarm audiences as much as the undead, though hopefully in a completely different way. The instrument belongs to Miss Caroline (Lupita Nyong’o), a kindergarten teacher who initially wields it to tame her class who are particularly rambunctious on their way to petting zoo for a field trip. Joining them is Stevens (Stephen Peacock), an out-of-work guitarist with plenty of free time on his hands who accompanies his nephew Felix (Diesel La Torraca), though he is he is far from the adult helper Miss Caroline could benefit from, still reeling from the recent revelation that his would-be fiancée has been cheating on him. While she knows she can calm down her students with an enchanting rendition of “Shake It Off,” she’s going to have problems putting those words into action with Stevens, who like so many before him begins to look at her in a romantic light.

However, if anyone’s well-suited to show grace under pressure, it’s Nyong’o for whom “Little Monsters” offers the kind of role that fans of the actress have likely long wanted to see her in, using her poise and elegance in service of a raucous comedy in which she remains unflappable while others panic. And panic they do when it turns out the petting zoo is located near a government facility where an experiment has completely gone awry, letting loose a fleet of flesh-eaters who make quick work of the goats and geese before setting their sights on the children. After previously slaughtering sacred cows with glee in the blistering (and still shamefully unreleased-in-America) race relations comedy “Down Under,” Forsythe shows a particular flair for commencing with utter carnage – even though the zombies move slow, they chew fast – and inserting Miss Caroline to lead the gaggle of five-year-olds to safety, both physically and mentally, insisting that the blood on her dress from dispatching a few of the undead is just strawberry jam, creates exactly the right combination of sweet and sour.

In fact, what makes “Little Monsters” stand apart from much of the genre is how heartfelt it ultimately ends up being, as Forsythe sneaks in a touching arc for Stevens, who grows into accepting more responsibility for himself while learning from Miss Caroline’s example in caring for Felix, and exploring how admitting your fears can be healthy. Yet as in any smart zombie movie, the writer/director knows to aim for the head first and piles on the biting humor, cunning wordplay and gruesome visual gags to entertain well before delivering the pleasant surprise there’s something going on underneath, not only making the most of the range of a perfectly cast Nyong’o and Peacock, but also enlisting Josh Gad to completely obliterate any goodwill he had with children from voicing Olaf in “Frozen” as Teddy McGiggle, a beloved kids’ TV host at the petting zoo for a shoot who’s completely rancid off-camera. It always feels like a small miracle when actors of a higher profile take a flier on such a subversive filmmaker as Forsythe with just a single film as a track record, but their trust pays off in this massively entertaining comedy in which it isn’t only the characters who show real growth, but its writer/director as well.

“Little Monsters” was acquired for distribution by Neon and Hulu.