The second Harry Potter movie adheres less minutely to J.K. Rowling's novels than the first, also directed by Chris Columbus, but more than the third, directed by Alfonso Cuaron. The median of the movies to date in both position and plan, Chamber of Secrets shows a fluid dynamism that advances tremendously from the sometimes stilted Sorcerer's Stone (2001), and an insistence on the symbolic otherness of wizard culture that surpasses Prisoner of Azkaban (2004). But I did not register those virtues the first time I saw the movie. Blinded by the accumulation of trifling canonical discrepancies -- from omitting the clue Ron finds in detention, to Professor McGonagall giving Professor Binns's history of the Chamber -- by the time the climactic basilisk confrontation rolled around, I could no longer resist jumping up from the DVD and grabbing the book to confirm that the giant snake ought to be smelling Harry instead of hearing him. Granted, my distraction was my fault for failing to take the movie entirely on its own terms. But does it ask us to take it on its own terms?

Chamber of Secrets sticks to the novel from which it sprang not only scrupulously, but conspicuously. More condensed than adapted, especially considering the deleted scenes, otherwise insignificant differences sit hesitantly, unsure of their welcome, calling attention to themselves. While Professor Lockhart still conveys the distastefulness of a lying braggart, the complicity of the media and his fan base almost vanishes, a lesson abridged from the book, instead of transformed to suit the movie. Similarly, the choice to underplay without substitution Ginny's poor judgment in trusting the diary -- chillingly like trusting a stranger on-line; also a soul poured into a material object that can give nothing back -- diminishes the final impact of the parallel evils: Lockhart, Tom Riddle and the monster are all creatures of vanished memories, with no more power than they can steal from others.

In both the book and the movie, Riddle is to Lord Voldemort as the basilisk is to Salazar Slytherin, and as Harry chooses to be to all Professor Dumbledore represents to him. But hobbled by its commitment to the book and its obligations to the series, the movie dares not reimagine those themes to make the cinematic points unachievable in prose. It preserves the shape of the book, as if the book is the story, not merely a fellow container for the story. It illustrates the great peril of the demand for absolute fidelity: shape rather than substance, stasis rather than growth.

Chamber of Secrets recapitulates the book excellently. Freed to reimagine the themes for its own medium, it might have done even more.