"The Way, Way Back" feels like the ultimate summer movie.

“The Way, Way Back” feels like the ultimate summer movie.

Of 1983.

No cities are leveled. No planets are ruined. The only thing that blows up is a relationship.

When we first meet 14-year-old Duncan (Liam James), he’s staring glumly out the back of his mother’s boyfriend’s 1970 Buick Estate wagon — the title refers to that rear seat — watching the world pass by. Trent (Steve Carell) asks how he sees himself on a scale of one to 10. Duncan meekly offers a six. Nope, Trent informs him, he’s a three.

When Duncan first meets his soon-to-be father figure, water park manager Owen (Sam Rockwell), it’s over a game of Pac-Man.

Two of the bigger laughs require at least a working knowledge of the band Mr. Mister and the soundtrack to “Footloose.”

Aside from the scene where the cute neighbor (AnnaSophia Robb) overhears Duncan awkwardly crooning along to REO Speedwagon — yet another relic from an earlier time — on his iPod, there’s very little to even place “The Way, Way Back” in this century.

And it’s all the better for it.

The movie, much like Duncan, gets off to a rocky start with his arrival in the Massachusetts coastal town where he’ll spend the summer.

Before we really get to learn anything about him, his mom (Toni Collette), Trent or Trent’s teenage daughter (Zoe Levin), they’re overwhelmed by Betty (Allison Janney, cranked up to 11). She lives next door to Trent’s beach house, which he’s christened The Riptide, and blows into the movie, and their lives, like a boozy hurricane, gossiping about everyone and everything and forever complaining about her young son’s (River Alexander) wonky eye.

It’s a lot to take in, but Betty’s your first clue that this is no place for a teenager. The beach is known as “spring break for adults,” where the grown-ups can spend their nights hooking up, getting drunk and smoking weed.

But Duncan’s biggest problem is Trent. During a boat trip, Trent entombs Duncan — and only Duncan— in a giant life jacket so no one has to worry about him. During a rainy day game of Candy Land, Trent angrily consults the rules to keep Duncan from improperly using the Gumdrop Pass. After this spring’s “The Incredible Burt Wonderstone,” Carell is firmly ensconced in the insufferable phase of his career, and he’s wonderful in his horribleness.

It’s no wonder Duncan can’t wait to get out of there. Even if it’s on the bicycle — pink, with lime green rims, a bell, streamers and a basket — he finds in Trent’s garage that eventually takes him to the fading Water Wizz water park.

Here, under the watchful eye of Rockwell’s Owen, Duncan and the movie finally come alive.

“The Way, Way Back” may be Duncan’s coming-of-age story, but it’s fully Rockwell’s movie. His frantic, rapid-fire delivery crackles with enough memorable lines for a dozen films. And he carries himself with the anarchic swagger of a young — well, young-ish — Bill Murray that gives the Water Wizz a welcome “Meatballs” vibe.

After cracking jokes about Duncan’s Toughskins jeans and trying his best to break through his clenched-fist awkwardness — “Wow,” he exclaims at one point. “Do you get comedy?” — Owen takes him under his wing, loans him an abandoned swimsuit from the lost and found, and introduces him to the other misfits at Water Wizz, played by “The Way, Way Back” writers and directors Jim Rash and Nat Faxon, who won Oscars for writing “The Descendants.”

There are some fun bits involving Rob Corddry and Amanda Peet as Trent’s bored friends. But there’s not enough of Corddry. (There rarely is.)

The scenes away from the water park are so realistically downbeat they can be uncomfortable to watch.

As Duncan, James barely registers. His growing confidence doesn’t feel earned, and he comes across like Logan Lerman Lite.

And as entertaining as Owen’s arrested-adolescent shtick is, he doesn’t necessarily feel like a real person — certainly not one you’d want to be around for more than a few minutes.

Still, the time you spend at Water Wizz just may be some of the most refreshing minutes you’ll have all summer.

It’s a cool blast of nostalgia for this or any decade.

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Christopher Lawrence is the movie reviewer for the Las Vegas Review-Journal. Contact him at clawrence@reviewjournal.com