Brian Cox as Dr. Finch and Annette Bening as Deirdre in "Running With Scissors."

“It doesn’t matter where I begin; no one is going to believe me, anyway.” So begins a voiceover by actor Joseph Cross, playing author Augusten Burroughs, whose popular memoir of a disastrously abnormal childhood and youth is the basis for this film adaptation.

This prediction proves to be apt. Running With Scissors is often richly entertaining, unsettlingly funny and compellingly frank in its rendering of colorfully mad compulsions. But it never really convinces us of its bona fide actuality. However much of it may be derived from real life (via the book), it comes off as creatively reworked.

The movie presents us with its Augusten, who in the late 1970s (at the age of fourteen) was handed over by his deranged, self-infatuated mother Deirdre (Annette Bening) to the care of her shrewdly exploitive but even loonier psychotherapist, Dr. Finch (Brian Cox). Augusten was sent to live among Finch’s freakishly dysfunctional family in a decaying pink mansion in an unidentified city.

Deirdre harbors demented assumptions about what she regards as her destiny as a great American poet, and sees her son as an encumbrance as she pursues her literary kismet.

Finch is only too happy to get Augusten, principally because it allows him to get his hooks even deeper into Deidre’s money. Despite a real professional license, he is to psychiatry what the Pied Piper was to babysitting, except that Finch’s motives are more self-serving.

The Finch family is something like the Addams family if they were led—dominated, actually—by a crafty, nutty Scientologist. Finch’s own muse is a parodically reinterpreted 1950s style Freud.

As put together by TV writer-director Ryan Murphy (Nip/Tuck), Scissors is certainly funny, frequently and in an awful sort of way, as it follows young Augusten observing and enduring various behavioral grotesqueries and insults. Murphy is an adept director scene-by-scene, but he hasn’t succeeded in making his movie cohere, either tonally or dramatically. When he is forced to confront the tragic undertow in Augusten’s crazy odyssey, he resorts to slightly out-of-proportion lyrical sentimentality.

The film’s strongest assets are the performances, which are all impressive (for which Murphy must be owed some credit). Bening’s is richly, forcefully conveyed. It’s also brave; in some scenes she allows herself to appear ravaged by age and inconsolable rage. The performance is sometimes larger than the movie, but it is riveting. Young Cross is an extremely able actor, giving Augusten a drolly distanced persona whenever he’s able to temporarily disentangle himself from the mad, sad proceedings around him. Jill Clayburgh as Mrs. Finch skillfully holds together a character that is unevenly written.

Running With Scissors is an unusual action showcase. What it isn’t is a subtle, insightful relation of a coming-of-age experience.