A CRYPTIC letter written by Beethoven to his "Immortal Beloved," which surfaced after his death, launched considerable debate over the years as to the recipient's identity. Her identity was finally established by Beethoven biographer Maynard Solomon in the 1970s. But without revealing the real woman's name, let us just say that "Immortal Beloved," a gothic-romantic mystery starring Gary Oldman, draws its own conclusions. Writer/director Bernard Rose not only comes up with a new mystery woman, he makes this forbidden love the key to everything about the Great Ludwig Van.

In the movie, Anton Schindler (Jeroen Krabbe) -- Beethoven's good-hearted friend and factotum -- discovers the letter and, to the horror of the late composer's greedy, family, decides to make this woman heir to Beethoven's estate and music.

He attempts to reconstruct Beethoven's romantic history by interviewing the composer's relatives, old flames and acquaintances, including countesses Anna Marie Erdody (Isabella Rossellini) and Giulietta Guicciardi (Valeria Golino); the proprietor (Miriam Margolyes) of a hotel where Beethoven apparently planned a tryst with the unidentified woman; and Beethoven's sister-in-law (Johanna Ter Steege), with whom the composer battled for custody of her son (Marco Hoffschneider). Through their recollections, shown in extended flashback, Schindler eventually establishes the identity of Beethoven's Immortal Beloved. "Immortal" is not a documentary. So the fact that Rose selects and rejects history as it suits his story is no fault per se. As Beethoven, Gary Oldman has some entertaining, stormy genius moments. He plays Beethoven as a bad-tempered, soon-to-be completely deaf , rogue lover -- a sort of classical Mick Jagger. And Rose, who made the visually compelling "Paperhouse" and "Candyman," creates some beautiful, surrealistic moments. But for all the story's illicit passion, creative reveries, detective-like investigation and twist ending, "Immortal Beloved" is episodically slow and surprisingly flat.

Rose doesn't help matters with a campy opening scene in which -- accompanied by the first four chords of the Fifth Symphony and a flash of lightning -- Oldman's aged, crackly face, and then his coffin, appear before us.

"He was an artist," comes Krabbe's reverent narration, "and who will stand beside him?"

With all that lightning around, who would want to?

Ultimately, the only reason to see this movie is for a handful of dreamlike moments: Beethoven as a child, lying naked in a lake, with the heavens reflected in the water; or the soundless moments when we -- like Beethoven -- can hear nothing but silence. Of course, the ultimate reason to visit this film is to hear its wealth of symphonies, concertos and sonatas. And luckily, musicians -- such as the London Symphony Orchestra (led by Sir Georg Solti), pianist Emanuel Ax and others, are much more faithful to the letter of Beethoven's original text than Rose. "Ode to Joy" and 57 years of other great pieces of music stand very much on their own.

IMMORTAL BELOVED (R) -- At the Cineplex Odeon Avalon. Contains nudity.

CAPTION: Oldman as Beethoven: Some entertaining flashes of genius.