Another year, another installment of the “Wimpy Kid” franchise, which began in 2010 with “Diary of a Wimpy Kid,” continued in 2011 with “Roderick Rules” and now reaches “Dog Days,” which unfortunately proves an apt subtitle. This was always a cable-quality series, and the new episode maintains the relatively low standards of the earlier ones without trying to raise them.

The movies aim to chart the learning curve of young Greg Heffley (Zachary Gordon), the likable middle child of suburbanites Frank (Steve Zahn) and Susan (Rachael Harris), bullied by older brother and would-be rock king Rodrick (Devon Bostick) and slyly abused by tyke Manny (Connor and Owen Fielding). In the first picture, Greg tried too hard to succeed in middle school, failing miserably but coming to appreciate the importance of his long-time friendship with chubby Rowley (Robert Capron), whom he’d been ready to abandon in his quest for popularity. In the second, he bonded with Rodrick, though the road to brotherly understanding was hardly smooth.

Now it’s Frank’s turn. “Dog Days,” set during the summer vacation that presumably follows seventh grade, finds Greg barred by his dad from playing video games all day and forced reluctantly to accompany Rowley to his parents’ country club to avoid “outdoor activities.” That proves fortuitous, however, because the club is not only a paradise of smoothies and empty swimming pools, but Holly Hills (Peyton List)—the girl Greg has a crush on—is a volunteer tennis coach there.

Unfortunately, to avoid having to take an internship at Frank’s office, Greg concocts the lie that he’s gotten a job at the club, which allows him to keep going there, although after an unfortunate incident with Rowley’s family he has to sneak in under false pretenses. There are also side plots, like Rodrick’s insistence that Greg get him into the club too, and Greg’s arranging for his bro’s band (Loded Diaper, ha-ha) to play at the sweet sixteen part for Holly’s snooty older sister Heather (Melissa Roxburgh), whom Rodrick is, of course, smitten with. And Frank forces Greg to join his old scout troupe, which leads to a slapstick confrontation in the woods with a smugly superior neighbor. Characters are also recycled from the earlier flicks—geeky classmate Fregley (Grayson Russell), tomboy rival Patty (Laine MacNeil) and Indian kid Chirag (Karan Brar)—but their appearances here are pretty fleeting.

What really continues from the previous pictures is the emphasis on Greg’s humiliation in the sort of icky situations young kids will find irresistible. “Dog Days” starts with a visit to an overcrowded public pool in which Greg has to put up not only with gross displays of other people’s flesh and being pushed around in the water, but suffering the indignity caused by some potty humor. Later he’s left swimsuit-less in the country club pool, getting all prune-skinned before having to don a pair of girls’ trunks to escape. There’s a doubles’ tennis match in which the hapless team of Greg and Rowley suffer a montage of head bonks and groin hits from Holly and Patty. And Rodrick gets into the act, not only by hiding repeatedly in a dumpster (with predictable results), but causing a disaster playing at the Hills’ party, complete with smashed ice sculptures and an unleashed chocolate fountain.

But the main thread of the script has to do with Frank and Greg’s father-son bonding, threatened by the boy’s lying about his “job” and by Frank’s meditation about sending him to a no-nonsense academy that will force him into line (occasioning a series of inserts about the school’s draconian methods). Though they appear to share nothing but an aversion to a “Family Circus”-style comic strip (a repeated gag that lands with a dull thud and closes with a tepid payoff), they learn to respect one another—partially through a yucky dinner-hour slapstick bit involving the family’s new dog—and express their mutual affection by picture’s end. The whole thing resembles nothing more than a fifties-style sitcom, with a moral that’s never in doubt, but boomers will probably relish having their grandkids learn the lessons of honesty and family ties.

Throughout Gordon remains an amiable presence, ably supported by Capron as dim but lovable Rowley. Bostick makes a snarky big brother, and Zahn bugs out his eyes with dangerous frequency to play the goofy Frank. Everybody else gets by at the level of a Disney channel original, and technically things are of cable quality, too, with the occasional burst of animation to mimic the books’ pages now seeming as tired as the entire series formula.

The movie does, however, leave one important question unanswered. What’s a buffoon like Frank doing reading Howard Zinn’s left-wing history of America? Does a hidden message lurk there, a subliminal suggestion to the youngsters who are the target audience? Is a conspiracy afoot?

Maybe the inevitable fourth chapter will reveal all.