"Ticket to Heaven," which begins an exclusive engagement today at the K-B Cerberus, is the kind of realistic topical movie that people were once accustomed to recommending because it felt undeniably "solid" and just as undeniably "hit home." A thoughtful, enlightening popular entertainment, "Ticket to Heaven" depicts the peculiarly harrowing psychological odyssey of a young man who drifts into an authoritarian religious cult, prompting alarmed friends and members of his family to unite in a conspiracy which succeeds in kidnaping and "deprogramming" him.

There hasn't been a Canadian feature this solidly absorbing and intelligent since "The Apprenticeship of Duddy Kravitz."

Recently, "Ticket to Heaven" won three major awards from the Canadian Film Academy--best movie, actor and supporting actor of 1981. Nick Mancuso, named best actor, had seemed a handsome mediocrity in the batty horror thriller "Nightwing." He does a phenomenal job in "Ticket," sustaining a complex, turbulent portrait of susceptibility and skeptical acuity, the mixture that allows the protagonist, David Kappel, to be lured into cultish self-effacement and then argued back to his senses.

Since Mancuso's eyes, face and body are keenly concentrated on reflecting the anguished self-consciousness in David, you feel as if you can always see and appreciate this interior mental combat. It seems a coherent turmoil when David is drifting away, coming back or floundering in midstream. An actor this attractive who can perfect a technique this expressive would appear to be dynamite star material.

The award for supporting actor went to Saul Rubinek, who emerges as a welcome, saner rival to Gene Wilder in the endearing role of David's good-humored, apprehensive best friend Larry, who spearheads the rescue conspiracy after receiving an abruptly terminated distress call and then encountering his unnaturally submissive old buddy in San Francisco in the custody of two cult chaperones. A junior ad executive in Toronto, Larry is introduced practicing his avocation, aspiring stand-up zany.

The screenplay, written by director Ralph Thomas in collaboration with Anne Cameron, is so skillfully constructed that the apparent irrelevance of this introduction, which shows Larry struggling to amuse an audience that includes a moody David, is eventually revealed to be essential, ironic preparation. When Larry himself ends up spending two disorienting days at the same communal retreat that broke down David's resistance, it's Larry's funny outlook and half-baked gift for comic improvisation that save him from falling victim to the strenuous, boisterous, evangelical peer pressure.

The movie is an astute fictionalized distillation of the narrative chapters in a nonfiction book called "Moonwebs." Written by a Montreal newspaper reporter, Josh Freed, it combined an account of his own successful conspiracy to extricate a good friend from a Bay Area youth organization.

Although Thomas is new to theatrical features, he spent a 15-year apprenticeship in Canadian television directing both documentaries and dramas. This may be Thomas' feature debut technically speaking, but it obviously reflects a seasoned and sophisticated technique, confident with actors, storytelling and semi-documentary depiction.

The sequence of David succumbing to the absurd yet insidious conviviality of the retreat is perhaps the best sustained example of Thomas' subtle skillfulness at showing processes at work. You begin to feel eerily enveloped in the peculiar sensory and emotional environment that ultimately locates a weak spot in David--a whirlwind of noisy play, chanting, sermonizing and communal soul-searching. Even if you consider yourself forewarned and hostile to this groupy, giddy preamble to indoctrination, which looks so silly and innocuous at first glance--like a convention of overaged Mouseketeers who may have slipped one aspirin too many into their Cokes--you begin to appreciate how the hubbub, the lack of privacy and rest, the protein-free diet and the mock-solicitous familiarity might get to just about anybody.

Thomas never underestimates the cultists. He doesn't demonize them either, although he clearly deplores the emotional blackmail, commercial profiteering and religious fraud they're ultimately obliged to practice. A menace certainly, but a menace of comprehensible, combatable human dimensions and part of the ongoing social history of a peculiarly vulnerable, delusion-prone generation, obviously far less wised-up or liberated than advertised way back in the '60s.

The excellent supporting cast includes a number of young actors who've made distinctive impressions before and confirm their talent as part of the "Ticket" ensemble. Meg Foster turns up as a kind of Sister Superior in the cult. Kim Cattrall, the orgasmic shrieker in "Porky's," is really much more amusing here as the insufferably peppy group leader at the retreat. Robert Joy, who played Susan Sarandon's good-for-nothing spouse in "Atlantic City" and the demented Harry K. Thaw in "Ragtime," thrives in yet another devious characterization as David's mentor on the flower-selling beat. Finally, R.H. Thomson, expertly droll as the hero's sidekick in "If You Could See What I Hear," demonstrates instant versatility as the abrasive deprogrammer who taunts David out of his pious stupor.