Some novels have great first lines. Beowulf has a great first word: “Hwæt.”

Nobody knows precisely what it means. Translators of the Anglo-Saxon poem generally regard it as a call to attention. Howell D. Chickering Jr. and Kevin Crossley-Holland separately have rendered it as “Listen!” Seamus Heaney, whose Beowulf was a best-seller in 2000, makes it “So.” Michael Morpurgo, the author of a new children’s version of the age-old tale, interprets it as “Hear.” Burton Raffel gives it a two-word treatment: “Hear me!”

Comparing these translations is a parlor game among Beowulf fans. So I wondered how the new movie based on the old story would handle the word. What would be the film’s first distinct sound? The answer: a loud burp, belched amid the clamor of a mead-hall beer bash.

That would be kind of funny, especially if the film’s script was more or less true to the original. But there’s really no other way to say it: The movie isn’t as good as the epic poem.

Beowulf is the first great example of English literature. Its 3,182 lines were written in Old English, which despite its name is essentially a foreign language. The Germanic tongue of the Anglo-Saxons took a decisive turn toward what we speak today after the Norman invasion of 1066. At any rate, Beowulf was written down about ten centuries ago and it probably comes out of an oral tradition that’s even more ancient. In terms of literary quality and cultural significance, the British Isles didn’t really produce a rival until the time of Geoffrey Chaucer, who wrote his Middle English tales in the 14th century.

The story of Beowulf has it all: a compelling central character, high-stakes conflict, and big fights with gruesome monsters. The poem’s commemoration of courage, loyalty, and generosity are strong themes. The tension between its Christian faith and pagan influences present probing questions about human nature, social structure, and religious history.

In key ways, then, Beowulf is made for the movies. In other ways, however, it falls short: There’s only the barest whiff of romantic intrigue, which most great thrillers manage to incorporate into their narratives. (The last really good movie I can recall that didn’t have any male-female drama was Master and Commander.)

The movie tries to compensate by altering the story. I’m no purist when it comes to turning old tales into movies. If script writers must take a few liberties with a classic, as they move from one medium to another, then so be it. Occasionally their deviations are improvements, or at least they open new whale-roads of assessment. (What’s a whale road? It’s a kenning. What’s a kenning? Look it up.)

The casting of Angelina Jolie as Grendel’s mother has attracted more attention than any other aspect of the new movie. This owes much to her celebrity, but perhaps even more to its sheer boldness. Grendel’s mother, after all, is traditionally portrayed as a wicked swamp hag. In the film, however, she’s a golden-skinned femme fatale.

This idea of Grendel’s mother sent me scrambling to my shelf of books on Beowulf: Was such a radical re-interpretation possible, somewhere in the silences of the poem? My quick conclusion was no. But it’s still an intriguing notion, I thought, and perhaps the moviemakers can pull it off.

Unfortunately, they don’t. I won’t include any spoilers here, so let’s just say that Grendel’s mother departs from the original in more ways than Beowulf can kill a sea monster. The same is true for other important characters. By the end of the movie, the script has made a complete hash of the story it’s based upon. Another non-spoiler example: The concept of Hrothgar as a self-absorbed, toga-wearing drunkard–as he is revealed to be in the first scene–is weird.

The film has several disappointing moments that would have been letdowns even in a faithful retelling. At the jam-packed screening I attended this week, the audience giggled over Grendel’s motive for attacking Heorat (he has really, really sensitive eardrums). During a scene in which Beowulf strips naked, the movie exhausts its creative energies to depict him in every pose possible and from all angles imaginable except one that displays his private parts. It manages the feat of being both distracting and ridiculous at the same time. Perhaps moviegoers who are less attuned to the poem will forgive these blemishes and enjoy the film on its own terms. The 3-D animation is eye candy. And the new storyline, for all of its wholesale invention, has its own logic.

When the credits rolled, however, I thought back to that burp at the beginning. It’s not a tongue-in-cheek salute to the poem. It’s a sign of disrespect.