IN SCOTLAND, MUM MUST BE SAVED.

Byline: Bob Strauss Film Critic

WHILE the sometimes brilliant British filmmaker Ken Loach's movies have recently let their socialist polemics overwhelm the characters who populate them, ``Sweet Sixteen'' re-rights the boat quite well.

Like Loach's best films - ``Kes,'' ``Riff-Raff,'' ``My Name Is Joe,'' ``Ladybird Ladybird'' - ``Sweet'' allows the detailed emotional struggles of people on society's lower rungs to do the speaking about larger economic and class inequities. And the results, as always, are far more stirring than the more propagandistic likes of ``Hidden Agenda,'' ``Land and Freedom'' and ``Bread and Roses'' inspire.

Employing, as he's sometimes done in the past, a cast of mostly first-time film actors, Loach here whips up a sad but deeply engrossing tale of an adolescent Scottish lad's determination to salvage his unsavable family.

Fifteen-year-old Liam (Martin Compston) knocks around the picturesque but depressed seaside town of Greenock with his best mate Pinball (William Ruane), pulling semi-legal pranks and eking out a living selling black market cigarettes. Raised primarily by state child services, bright Liam and troublemaking Pinball are more than friends; they've relied on each other, like no one else in either of their lives, since they were little.

Unlike Pinball, though, Liam technically has actual relatives. His rotten grandfather lives with the drug dealer Stan (Gary McCormack). Liam's junkie mom, Jean (Michelle Coulter), took the rap for one of lover Stan's crimes, and is due to get out of prison in 10 weeks - just in time for her son's 16th birthday.

But Liam rightly despises Stan, and determines to create a better life for his mother to come home to. So he moves in with his older sister, Chantelle (Annmarie Fulton), herself an unwed teenage mother also trying to better her lot. The trouble is, Chantelle long ago gave up on their mother, while Liam has convinced himself that, just given the right chances and environment, Jean can become the responsible and loving parent he longs for her to be.

To this end, Liam and Pinball steal Stan's heroin stash and set up their own dealing business. This gets the boys into much hotter water with much bigger underworld fish, but if Liam cheeks it out right, this could work to their greater economic advantage. Impulsive, self-destructive and car-theft-prone Pinball, however, could be a problem - as if dealing narcotics to save Jean from enslavement to them isn't.

While the plot, by regular Loach scriptwriter Paul Laverty, owes more than a few props to ``Mean Streets,'' the kitchen sink naturalism here marks ``Sweet Sixteen'' as anything but another Scorsese rip-off. Presented in thick Scottish dialect with English subtitles (they're necessary), the film convincingly captures youth's heedless longings and the mad - if completely logical to them - lengths some kids will go to to realize quixotic dreams. It's heartbreaking and scary to watch a smart, damaged kid with the most admirable of intentions dig himself deeper and deeper into an ethical pit that he can't even comprehend, while we see his future and soul careening toward ever greater jeopardy.

But tragic as it all is, ``Sweet Sixteen'' keeps the hand-wringing in check. A lot of it is almost jaunty. Despite their hopeless situation, these kids are funny, enterprising and admirably strong both physically and emotionally. Chantelle, who dearly loves her brother despite their differences regarding Mum, explains - while patching him up from the umpteenth beating he's taken like a man - that what worries her most is the suspicion that he doesn't feel anything.

Of course, plucky Liam's real misfortune is that he feels too much for the wrong people. Ultimately, ``Sweet Sixteen'' is the story of a peculiarly selfish form of self-sacrifice, one that no one but a teenager with an overabundance of moralistic impulse but no realistic moral framework can indulge.

SWEET SIXTEEN - Three and one half stars

(R: violence, language, drug use, children in jeopardy)

Starring: Martin Compston, William Ruane, Annmarie Fulton, Michelle Abercromby, Michelle Coulter, Gary McCormack, Martin McCardie.

Director: Ken Loach.

Running time: 1 hr. 46 min.

Playing: Galleria Stadium 16, Sherman Oaks; Playhouse 7, Pasadena; Sunset 5, West Hollywood; Westside Pavilion, West L.A.; Monica, Santa Monica; University 6, Irvine.

In a nutshell: Touching, realistic tragedy about a Scottish adolescent's doomed efforts to make a decent life for himself and his junkie mum when she gets out of prison.