On a scale of one to 10, Duncan rates himself a six, after being prodded to pick a number by the bully who's driving. "A six?" Duncan's mother's boyfriend Trent says, bouncing disdain off the rearview mirror. "I think you're a three."

The insult smacks Duncan from behind, sitting in "The Way, Way Back" of a vintage station wagon in a reversed rear seat. Mom's asleep but she's too needy in love to protest. Trent's daughter Steph may be faking sleep, deflecting dad's scorn to Duncan.

It's the start of the summer that Duncan will never forget, for all the eloquent and awkward reasons "The Way, Way Back" shares with countless coming of age movies.

The movie is written and directed by Nat Faxon and Jim Rash -- he lived through being rated a three who won Oscars for scripting "The Descendants," a gig resulting from this screenplay floating through Hollywood for years. The movies share ideas of domestic splits and disloyalty, selfish grownups and children caught in the middle. You might even compare Hawaii's beach appeal with coastal Massachusetts and the Water Wizz water park where Duncan takes first steps to the next, better stage of his life.

Duncan is portrayed with gawky grace by Liam James, smartly measuring his character's growth with gradual shifts in posture, eye contact and expression. The movie begins and ends with Duncan in that way, way back seat, but it's a different person at the fade out.

"The Way, Way Back" richly details both sides of Duncan's summer, each marked by adults in states of arrested development. Owen's is amusing, with pranks and banter inspiring a wacky sense of family among Water Wizz employees. Trent's is annoying, a me-first attitude enabled by Duncan's mother Pam (Toni Collette), and summer neighbors like a boozy busybody next door (Allison Janney) and a pushy party couple (Amanda Peet, Rob Corddry).

The jokes are often double-edged, the performances always spot-on. The Way, Way Back doesn't re-invent the teenage turning point genre, but Faxon and Rash offer a breezy new spin. You'll see more inventive movies this year but few more endearing.

"The Way, Way Back" is rated PG-13; profanity, mature domestic themes, brief drug material.