It doesn't help matters that his more freewheeling twin brother, Donald (NICOLAS CAGE), has decided to take up screenwriting as well. Having attended classes by screenwriting guru Robert McKee (BRIAN COX), Donald turns out to have a knack for it despite doing everything that Charlie believes is wrong from an artistic standpoint. Unlike his brother, Donald has no problem with the ladies, whether it's Amelia (CARA SEYMOUR) or make-up artist Caroline (MAGGIE GYLLENHAAL).

As Charlie attempts to write this story that he believes isn't filmable, we see flashbacks of Susan at work at the New Yorker writing her book, as well as ones even further back where she interviews and eventually falls under the spell of her titular subject, John Laroche (CHRIS COOPER), and his passionate lifestyle and mindset.

With time running out, Charlie tries various ways of finishing his script, ranging from finally meeting Susan to actually writing himself and his brother into the story.

The problem, however, is that such insider material can become so thick, removed and/or circular that it bogs down the production or sets up expectations that aren't or can't be matched. Some of that applies to "Adaptation," the highly anticipated follow-up from the filmmakers responsible for the critically acclaimed and wildly imaginative "Being John Malkovich."

In this effort, a neurotic screenwriter -- Nicolas Cage ("Windtalkers," "The Family Man") playing Charlie Kaufman, the real-life writer of both this film and "BJM" - is trying to adapt a novel - "The Orchid Thief" by real-life author Susan Orlean played here by Meryl Streep ("The Hours," "Music of the Heart") - but is creatively stymied. His effort eventually involves writing himself into his own script, an offbeat development that obviously occurred in real-life with the real Kaufman. Accordingly, that results in a film showing its own inner workings and creation.

That description might sound somewhat confusing and perhaps not as amusing or clever as it really is, but that bizarre quality shouldn't come as a surprise considering that Kaufman ("Confessions of a Dangerous Mind," "Human Nature") and director Spike Jonze ("Being John Malkovich") are the creative force behind the effort. Hopping, skipping and jumping through time, stories and ultimately interwoven realities, the plot is all over the place, but that's part of its wacky charm.

It's not only an examination of the creative writing process, but also of the human condition, particularly related to passion. Through Cage's voice over narration, we hear the neurotic inner workings of the insecure writer's mind at work, and for anyone who's ever suffered from writer's block, the narrative is both accurate and a complete hoot. One needn't have experienced that or seen "Being John Malkovich" to enjoy what's offered here, but the more knowledge one has regarding either or both, the more entertaining everything will likely be.

That said, the film does have a weak third act that partially belies what was built up before it, especially regarding the art of writing and not selling out for commercialism. It also contradicts a point that it makes regarding its own finale, although both "faults" seem to be intentional.

Whatever, the case, part of the running joke in the film is that the protagonist's more self-assured twin brother - also played by Cage - has suddenly decided to take up screenwriting as well. No one knows if Donald Kaufman exists in real life or is just the screenwriter's alter-ego, but the character here takes a screenwriting course taught by legendary writing instructor Robert McKee who's played by Brian Cox ("The Ring," "The Bourne Identity") in a terrific impersonation.

Part of the joke is that McKee's course is all about formulaic structure and making a script commercially viable, to which Charlie and thus apparently the film, aren't interested in conforming. Whether it's part of the film's "in" joke is debatable, but the third act pretty much throws out the wildly imaginative material in favor of more "commercial" elements. I believe I understand what the filmmakers were striving to say and/or accomplish since all of that comes about after Charlie the artist asks Donald the clichéd writer for help, but it still doesn't really work that well.

In addition, at one point McKee teaches that a terrific and memorable ending will make a film a winner and cause the viewer to forgive most of its earlier faults. That, of course, builds up expectations of some wild finale for this already quirky film. Yet, the film's conclusion is its weakest point, satire or not.

While the unexpected does occur, the developments as well as the way they're handled are incongruous with the rest of the film. The ending would have been disappointing in any event, but the built-up expectation only makes it that much more of a letdown, particularly in comparison to all that precedes it.

That includes fabricated "behind the scenes" material on the set of "Being John Malkovich," some terrific and often quite funny dialogue, and the plot that repeatedly folds in upon itself while alternating its focus on various parts of the story that relate to or directly affect later - or earlier -- ones.

As the tortured writer and his more freewheeling brother, Cage is terrific and pulls off a convincing dual performance playing off himself. Streep, as usual, is solid, although those late in the game developments don't work that well, even if they somewhat make sense - at least in theme - regarding what her character is going through.

Chris Cooper ("American Beauty," "October Sky") is also quite good playing a variation of the Renaissance man who moves on from one vocation to the next with ease and no worries. His performance is fun, engaging, and could earn him some award nominations. Supporting performances from the likes of Maggie Gyllenhaal ("Secretary," "40 Days and 40 Nights") and Tilda Swinton ("Vanilla Sky," The Deep End") are fine.

If not for the disappointing third act, this would be a real gem of a movie lover's movie, what with all of its inside jokes, keen observation on the creative process and the fact that we're essentially watching a dramatic and quirky reenactment of the film being made within itself. Fun and decidedly offbeat, but probably not for everyone's tastes or liking, "Adaptation" rates as a 7 out of 10.