Every filmmaker has a unique origin story. Matt Reeves’s involves Super 8 cameras and dolphins.

One day, when Reeves was around 8 years old, his grandparents took him on a trip to a Southern California ocean-themed entertainment park called Marineland of the Pacific.

“There were some tourists filming dolphins with an 8-millimeter camera, and it hit me like a lightning bolt,” Reeves recalled on a mid-June morning in his office on the 20th Century Fox lot. “I thought, ‘Wow, they’re going to have the dolphins! Any time they want, they can put the dolphins on their wall!’ I was blown away by that. My grandfather sent me my father’s old wind-up 8-millimeter camera, and that was it. I never turned back.”

Forty-odd years later, Marineland has long since closed, but Reeves’s passion for capturing stories on film has never dimmed. The only difference is that the technology has advanced – and, for the moment at least, Reeves is all about apes, not dolphins.

On Friday, Reeves’s latest film, “War for the Planet of the Apes,” rode into theaters like a silverback gorilla on horseback, boosted by the kind of enthusiastic buzz any director of a summer blockbuster would kill for. The third installment in the recently rebooted sci-fi series – and the second to be directed and co-written by Reeves, following 2014’s smash “Dawn of the Planet of the Apes” – the film brings the ongoing struggle between humans and sentient simians to a head, as the ape leader Caesar (Andy Serkis) squares off against a ruthless colonel (Woody Harrelson).

“War for the Planet of the Apes” is the third in the “Apes” franchise and the second directed and co-written by Matt Reeves. Photos courtesy of Twentieth Century Fox via AP

Part “Apocalypse Now”-style meditation on the madness of war and part Sergio Leone-esque western, with a dollop or two of biblical epic added for good measure, “War for the Planet of the Apes” is a headier, more ambitious concoction than one typically expects from summer-tentpole fare these days. But as Reeves sees it, the franchise’s secret sauce is its ability to sneak in meaty stories and nuanced characters under the cover of talking apes.

“If it weren’t for the fact that we have photorealistic apes in the story, we wouldn’t be able to make this movie,” said Reeves who, on the strength of his work on the “Apes” franchise, has been tapped by Warner Bros. to helm a solo Batman movie. “It wouldn’t be a $190-million Fox movie. But watching these apes and feeling their humanity – it creates just enough distance and enough spectacle that the audience is really excited about seeing that kind of thing.”

Dating to 1968’s original “Planet of the Apes” – with a few goofy, misbegotten sequels, spinoffs and attempted reboots along the way – the “Apes” franchise may seem an unlikely candidate for such serious treatment all these years later. But from the moment he came on board, following Rupert Wyatt’s successful 2011 reboot “Rise of the Planet of the Apes,” Reeves saw the thematically rich, even Shakespearean potential in the franchise.

“On ‘Dawn,’ Matt just went with the drama, and that’s been his maxim all the way through,” said Serkis, whose performance-capture work as Caesar has drawn widespread acclaim. “When you look at what’s around, I feel incredibly privileged to be part of a blockbuster movie where it is an intelligent take, where you can connect with an audience in a real and visceral way and not have it be just purely entertainment. It’s such a tonic and a wake-up call.”

Indeed, in a summer that has seen a number of would-be blockbusters such as “The Mummy” and “King Arthur: Legend of the Sword” take it on the chin at the box office, “Apes” producer Dylan Clark believes Reeves’s effort to elevate the “Apes” franchise will be rewarded, as it was with “Dawn,” which grossed $710 million worldwide.

This image released by Twentieth Century Fox shows a scene from, “War for the Planet of the Apes.” (Twentieth Century Fox via AP)

“When you’re doing big spectacle tentpole movies, it could be easy just to let the visual effects and the noise take over,” Clark said. “But what we’re seeing is that the audience wants to connect emotionally. If you have a director like Matt, whose empathy is the thing that leads him into the story, chances are they’re going to connect to the characters.”

In conversation, Reeves comes across as genial but somewhat shy and soft-spoken. (“I’m a naturally anxious, nervous person,” he said.) Even though his temperament may be at odds with the stereotypical image of the hard-charging, alpha director, no one should underestimate him for a moment, said “Apes” producer Peter Chernin.

“Matt is very quiet – I’ve never seen him raise his voice or even be particularly tough,” Chernin said. “But he has a very singular vision. He’s one of the rare people I’ve ever met who’s both a big effects-driven spectacle filmmaker and also a phenomenal actors’ director.”

That said, Reeves’s ascent to the top ranks of Hollywood filmmakers has hardly been a straight line. In recent years, studios have been turning with increasing frequency to relatively untested young directors to helm tentpole films, the most recent example being Jon Watts, who leaped directly from the low-budget, little-seen “Cop Car” to this month’s “Spider-Man: Homecoming.” At 51, Reeves has been plugging away in film and television for more than 20 years in what he called “a long, weird, circuitous journey.”

Early in his career, inspired by the auteur-driven cinema of the ’70s, Reeves imagined himself making idiosyncratic, personal movies in the vein of Hal Ashby, who directed such films as “Harold and Maude,” “Shampoo” and “Being There.” But when his directorial debut, 1996’s David Schwimmer-Gwyneth Paltrow romantic comedy “The Pallbearer,” landed with a thud, his hopes of being celebrated as an exciting new voice in cinema quickly faded.

“You have all these dreams – you’re going to break in and make your first big statement – and very rapidly it all collapsed,” he said. “It was a shocking thing. I didn’t know how I was going to recover – or if I was going to recover. But what it taught me was tenacity. It created a tremendous urgency to find a way to continue.”

Reeves pivoted to television, co-creating the series “Felicity” with his longtime pal J.J. Abrams, whom he had befriended at age 13 over a shared love of making Super 8 movies. In 2007, more than a decade after his filmmaking career had exploded on the launching pad, Reeves was asked by Abrams if he’d be interested in directing a found-footage monster movie he was producing called “Cloverfield” – a project that seemed far outside Reeves’ wheelhouse.

“I was like, ‘What are you talking about? Why should I direct this movie?'” Reeves said. “J.J. said, ‘Because you’re going to try to ground it and make it real – that’s what you do.'”

Made for just $25 million, the film grossed $170 million. Much to his surprise, Reeves was suddenly considered a genre filmmaker, a reputation he cemented with his well-received 2010 teenage vampire film “Let Me In,” a remake of the Swedish film “Let the Right One In.”

Having grown up loving films like “Star Wars” and “Planet of the Apes,” Reeves has come full circle and now fully embraces sci-fi, horror and fantasy. “At the beginning of my career, I don’t think I understood just how personal genre could be,” said the director, who is helping develop a TV series based on Justin Cronin’s bestselling vampire novel, “The Passage.”

As he looks ahead to his Batman movie, Reeves is well aware that the stakes for his career have been raised far beyond anything he ever imagined as a little kid watching tourists film dolphins on their Super 8 cameras. In today’s Hollywood, a superhero film has the potential to either send a director’s career soaring or bring it crashing to earth in a single weekend.

“There are definitely ‘Apes’ fans who are excited to see this movie, but it’s not the same thing as a Marvel fan or a DC fan,” Reeves said. “There is a lot of pressure. But there’s no possible way to give everyone what they’re expecting because everybody is expecting something different. The only thing you can really do is dig down as deep as you can to present as personal a version of that story that resonates with you. At least that’s my approach.

“I never thought I would be making these kinds of movies,” he said. “The path of my career has been totally unexpected to me. And yet it’s all been rooted in the same thing, which was to try to feel my way through instinctually to the kinds of stories that I can relate to.”

He shrugged. “It’s a funny path, but I guess that’s the way it always is, right?” he said. “Things never happen exactly the way that you imagine they will.”