Behind deliberately ambiguous advertising, Brothers of the Head ventures three things, gets one of them not all that much; the second, fair-to-middling, though managing quite well with a corollary; and the third, truly smashing and, especially today, sane and long overdue.

Having already collaborated on a 1996 portrait of Terry Gilliam, directors Louis Pepe and Keith Fulton got to know scriptwriter Tony Grisoni during Gilliam’s famous abortive Quijote adaptation, out of which developed their own darkly ironic Lost in La Mancha. Although the directors’ feature collaborations had been non-fictions, they were impressed when Grisoni gave them a copy of the Brian Aldiss book of made-up “interviews” to which he had obtained an option three decades before.

In Aldiss's 1977 illustrated dream-inspired novella, conjoined Siamese twins Tom and Barry Howe are talked about but unseen. At first conceived for the screen “as a kind of documentary” along the same lines, their duo-solo story grew, until the major component of pure plot became the twins, their problematical physical maturation, the uniqueness of each combined with the two’s shared life, their subliminal longing for pre-birth post-death release, and at least one, and possibly both, brother’s decline in the substance-abuse environment of celebrity excess.

The controlled supporting cast admirably avoids leering tongue-in-cheek, and, as Barry and Tom, identical Devonshire twins and first-timers Luke and Harry Treadway are uncomfortably harnessed together and terrific in conveying a mix of frustration, love, anger and irony, Tweedledum and Tweedledee but simultaneously Barry and Tom. Despite the acting, however, story is the weakest of the three links, because this rock ‘n’ roll rags-to-riches drugs-and-sex unhappiness has been done to death in biopics, documentaries and fiction films.

On a second, also often considered level, Brothers works better and, underlined by its impresario’s “’and over me ‘eart, I never exploited anyone . . . who didn’t want to be exploited,” digs especially hard at the manipulative circus nature of packaging culture and hysteria for the consuming younger set. Sold at eighteen by their widowed father to promoter Zak Bedderwick (Luke Wagner when young; then by Howard Attfield), the L’Estrange Head country boys are transported to an estate where their stage education is entrusted to musician Paul Day (Bryan Dick in the 1970s; David Kennedy in the present) and manager Nick Sidney (Sean Harris).

Though gentler Tom will never be mistaken for Robert Cray or Stevie Ray Vaughan, he learns a passable guitar, while, punched into line, intractable Barry scribbles and screams out the obscene lyrics that make them and their band a punk phenomenon in the late-‘70s pub scene. Sprinkled with excessive gimmicky intercuts of the younger twins running from the camera over a rippled surface, of a solitary cottage “Rosebud”-reminiscent of childhood freedom, of vaguely uterine fetal stirrings, the film is more successful than most others in imaging the self-indulgence of performance culture gone amok and the well-meaning but fatal dragon lady.

With press-packet thumbnail “biographies” of the boys, dated “archival” and “movie” inserts, Pennebaker-Maysles-type “concert” footage, and years-later “assessments” by the boys’ older sister “Robbie” (Roberta, played by Elizabeth Rider), fellow rockers, hangers on, groupies, lawyers (Henry Couling, by Ken Bones) and lovers (journalist Laura Ashworth, by Tania Emery then, Diana Kent now), author Aldiss (James Greene), photographer Cilla (Anne Lambton), documentarian Eddie Pasque (Tom Bower) and film director Ken Russell (himself) and trotted-out surgeons and radiologists (Jeffry Wickham, Barbara Ewing), the fun yet deadly serious film makes its point, although a few viewers did not notice and were caught unawares or unbelieving by a modest end-credit disclaimer.

By virtue of its manner, the story would, in effect, slip the wool over the audience’s collective but conditioned eye. Fiction and fact, illusion and reality -- indeed, the nature of such concepts -- blur, overlap, merge, dangerously so, for we accept as true that which is told as if it were. Identified by the usual print undertitles, for example, talking heads are assumed to be veracious and their participatory or objectively educated comments duly noted down. Written fiction’s ploy of the unreliable narrator has become lost, and a McLuhan society will buy just about anything.

Not at heart an in-joke, spoof or mockumentary, Brothers of the Head convinces, or comes close enough to be discomforting, that, in spite of hints -- e.g., a previously dormant third fetus head -- it emerges as disturbing reflection on what we, and not “the freaks and ghouls,” have been molded into. 

(Released by IFC Films and rated "R" for language, drug use and sexuality.)