By Jocelyn Noveck, AP National Writer

Consider it an early Christmas gift: "Anna and the Apocalypse" is the zombie horror holiday musical you didn't know you needed.

Just imagining that first pitch meeting is entertainment in itself. "It's 'High School Musical' meets 'World War Z!' No no, it's 'Glee' meets 'Shaun of the Dead!' Hold on … it's Christmas! OK, 'Love Actually' meets 'The Walking Dead!'"

Whatever its cinematic antecedents, "Anna," which boasts an appealing cast of fresh-faced newcomers and a quirky Scottish sensibility, is charming, often clever, and unexpectedly moving, too. And who's to say we're not ready for a zombie horror holiday musical? Compared to your average TV newscast these days, it's positively relaxing.

The film, directed by John McPhail with catchy original songs by Roddy Hart and Tommy Reilly, has a sad backstory. It's based on a BAFTA-winning short film, "Zombie Musical," by Ryan McHenry, who died at age 27 of cancer in 2015 just as his project was on the way to becoming a feature film. (He shares a writing credit here with Alan McDonald.)

The new film has the undeniable asset of Ella Hunt in the lead role, charismatic and touching as teen heroine Anna. At 18, Anna is ready to graduate high school in her small Scottish town of Little Haven, and keen to experience the world. As we begin, she's informing her dad (the perfectly cast Mark Benton), who's raising her alone, that she plans to postpone university and travel to Australia. He is NOT amused.

Dad's the janitor at Anna's high school, which is run by a misfit headmaster, Savage (Paul Kaye, whose sneers become nastier by the minute.) The first part of the movie — we'll call it the "High School Musical" section — introduces us to the typical slate of teen characters and their struggles. To name a few, there's Anna's best friend, John (a highly likable Malcom Cumming), the nice guy who secretly loves her; there's army brat Nick (Ben Wiggins), the conceited bully who's dated and dumped her; there's Steph (Sarah Swire, who also choreographed the musical numbers!), a brooding aspiring journalist neglected by her wealthy parents. Everyone's coping with the usual teenage pressures as they seek to define themselves and prepare for imminent adulthood.

What they don't expect is, um, a zombie apocalypse. It happens suddenly one day. Heading out of the house, Anna puts her headphones in and sings cheerfully of a beautiful new morning. "What a time to be alive," she sings, and dances, oblivious to the murderous zombie mayhem happening in the suburban streets around her. It's the film's most entertaining number.

Finally Anna and friend John, also dancing away the morning, meet up in a playground, where they have a head-spinning encounter with a zombie dressed as a snowman. Panicked, they head to the bowling alley where they both work. There, alas, they find a lot more zombies. Director McPhail finds inventive ways to stage zombie gore, including, yep, zombie heads popping up in the bowling ball dispenser. (We'll let you picture that for a second.)

The dialogue can be quite funny, as when the teens contemplate the fate of their favorite celebrities. Justin Bieber's a zombie, one of them exclaims. Ryan Gosling? "Alive, dead, the guy's still cool," another reasons. But the idea that Taylor Swift might be a zombie is too much for one: "Tay-Tay's fine!"

The latter part of the film, and it does get to feel a bit long, becomes a more traditional zombie narrative, a fight to the death for our spirited band of teenagers seeking to escape the deadly bite and reunite with loved ones, if they're alive. For Anna, it's about finding her father. Her face streaked with blood, killing zombies with nothing but an oversized candy cane for a weapon, Anna fights with the tenacity and fury of a Scottish Katniss Everdeen.

And yet, this being a musical, she still finds time to sing.

Her back up against the wall, she sings that if she's gonna die anyway, "I'll give them one hell of a show." And so she does. By the end, you may find yourself wiping away a few tears. Somehow, this amusingly chaotic mashup of genres finds a way to strike a final note that's simple and true.

"Anna and the Apocalypse," an Orion Pictures release, is rated R by the Motion Picture Association of America "for zombie violence and gore, language, and some sexual material." Running time: 97 minutes. Three stars out of four.

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