Director Danny Boyle poses for photographers upon arrival at the World premiere of 28 Years Later on June 18 in London. Photo by Scott A Garfitt/Invision/AP

Danny Boyle’s “28 Years Later” is his long-awaited sequel to “28 Days Later,” the 2003 post-apocalyptic zombie film that rejuvenated the entire genre. How did it do that? Boyle gave us zombies who sprinted, rather than slowly, aimlessly shuffling along, and brought a 21st century energy and unease to a worn-out horror cliché.

Rather than the new film becoming a forced retread or an easy cash grab, Boyle has doubled down on what made the original film distinct and disturbing, resulting in a new chapter that is a true rarity — a sequel that is much better than the original.

A harsh opener reminds us of the early days of the zombie outbreak of the first film, where a room full of scared children enduring reruns of Barney the Dinosaur are not distracted from the madness occurring outside. If this unsettling sequence rattles you (even I was shaken by it), you may want to tap out immediately.

The story jumps to 28 years later, where a remote island provides a well-protected village and home for the surviving humans. Essential ventures outside and onto a path that leads across the ocean is where brave humans seek food or goods in a land where zombies appear at random.

The duo who decide to explore the zombie-plagued terrain are Jamie (played by Aaron Taylor-Johnson) and his 12-year-old son Spike (played by newcomer Alfie Williams). The only threat to Spike more immediate than zombies is the fading health of his mother (played by Jodie Comer), who he aims to keep alive.

Written by Alex Garland, author of last year’s best film “Civil War” and challenging genre films like “Annihilation” (2018) and Boyle’s “Sunshine” (2007), Boyle has once again found his aggressive visual style is well matched for Garland’s tendency to horrify and emotionally engage his audience.

“28 Years Later” frequently toggles between being amazing and nauseating. There’s a moment early on where a zombie slurps a long earthworm into its mouth. It was enough to make me abandon my popcorn.

In addition to the vivid carnage (even for a mainstream zombie flick), some of Boyle’s music choices are hard on the ears.

Here is a rare summer movie that gets better as it moves along, but the first hour is often an assault on the senses. Boyle is still editing his films like he’s shooting a Nike ad, a choice that actually benefited his best film, “127 Hours” (2010).

A key reason why “28 Years Later” works so well is that you’ll care about the human characters and won’t root for their grisly demise. That may not sound like much but considering how many horror films are mere excuses for mayhem (with death scenes of main characters being chalked up as “kills”), it makes a difference when you can feel the stakes and are rooting for and not against the protagonists.

Unlike the original, in which Cillian Murphy’s central character roams through a seemingly empty, unoccupied London (still the best portion of that movie), we have a father-son saga, exploring how boys initially gravitate toward their dad, then come to a crucial decision on whether they truly want to be like them or go another way.

It’s actually a better adaptation of Cormac McCarthy’s “The Road” than the actual movie of “The Road” (2009).

The acting is exceptional. Taylor-Johnson survived starring role duty in “Kraven the Hunter” (2024) and reemerges as the ferocious character actor who caught my attention in “Nocturnal Animals” (2016).

Comer, in one of the film’s hardest, trickiest performances, continues her hot streak as a striking new talent to watch. Ralph Fiennes, playing a character who appears late in the film and worth shrouding in mystery, is, likewise, superb at playing a figure who poses so many challenges to lesser actors. Fiennes’ work here is among his best, which is really saying something.

Yet, it’s Williams who carries the film, as Spike is the heart of the story. Rather than coming across as amateur or outmatched by the material, we never doubt Williams’ performance or the character. He’s that good.

Boyle is having good luck with sequels: his “T2: Trainspotting” (2017) is an excellent follow up to “Trainspotting” (1996), his career defining breakthrough. Now, by returning to the genre he turbo-charged at a time when zombie movies were as slow, lumbering and indifferent as the undead creatures themselves, he has again elevated the genre.

(3 stars out of 4)

Barry Wurst II is the founder of the Hawaii Film Critics Society and teaches film classes at University of Hawai’i Maui College.