With “December Boys,” Harry Potter joins Ron Weasley in being introduced to the mysteries of the opposite sex. Ron—or Rupert Grint, to be more accurate—lost his virginity some months back in “Driving Lessons,” in which he played the young aide to an aging actress who was bedded by a more experienced lass during a car trip to Scotland. Now Daniel Radcliffe, Harry himself, is a student at a Catholic orphanage in the Australian outback who succumbs none too reluctantly to the allure of a local girl while on holiday at a seaside village in Rod Hardy’s sweet—indeed, cloying—coming-of-age tale, scripted by Marc Rosenberg from a novel by Michael Noonan.

But the deflowering of Mr. Radcliffe’s Maps, as the rather dour young man is called, by the gregarious Lucy (Teresa Palmer) is but one of the life-changing experiences that he and his younger chums—Misty (Lee Cormie), who narrates the tale from many years later, Spark (Christian Byers) and Spit (James Fraser)—have during their Christmas stay with jovial ex-Navy man Bandy McAnsh (Jack Thompson) and his wife, affectionately nicknamed Skipper (Kris McQuade). They also find themselves locked in competition that threatens their friendship when a childless couple—Fearless (Sullivan Stapleton), who passes himself off as a motorcycle daredevil at a nearby carnival, and his winsome French wife Teresa (Victoria Hill)—decide that they might just adopt one of the lads. They must deal with the reality of loss when one of their new friends falls very ill. And, in a plot device that all too heavily comments on the cycle of life and the need for something to aspire to, they come to sympathize with a grizzled, grumpy old fisherman who’s eternally trying to catch a legendary fish that’s been swimming in the lagoon since anyone can remember.

Alone any one of these plot threads would seem heavy-handed; taken together they’re positively lethal, and a retrospective coda that strives to cause a lump in your throat by having the elderly Misty sum up everything is likely to produce a grimace instead. There are compensations: the production design (Les Binns), art direction (Andrew Walople) and costumes (Marriott Kerr) capture the period very nicely, and the locations are attractive, and nicely caught by Dave Connell’s gauzy but effective cinematography.

By and large the performances fill the bill, too, though the greatest problems arise in the most serious cases. As young Misty, Cormie is encouraged to play for sympathy overmuch—the character is nicknamed for his tendency to weep, and the filmmakers obviously want him to have a similar effect on the audience. And Radcliffe is never given the opportunity to proceed beyond a sullen brooding; Maps turns out to be a one-note figure, and though Radcliffe hits that note squarely, it’s not a role that allows him to demonstrate his range. On the other hand, Byers and Fraser come off better, simply because they’re required to bear less of the script’s more ponderous aspects, while Palmer is actually quite engaging as Lucy. And all the adults fare reasonably well, with Sullivan showing an easygoing charm as the cycle-driving husband with grief of his own to shoulder.

“December Boys” will satisfy tolerant audiences looking for a dose of bittersweet nostalgia. And it will be mandatory for those interested in watching Radcliffe struggling to mature as an actor. But the barrage of messages it carries ultimately proves too heavy a cargo for Hardy’s creaky vessel to bear.