Wikipedia:WikiProject Novels/Harry Potter task force/Notability/Differences/CoS

Chamber of Secrets is the Harry Potter film which, in the eyes of many fans, remains truest to the original novel.. Very few plotlines are entirely absent from the film adaptation, although some are condensed on account of time considerations. Many of the more truncated themes were originally written in a more comprehensive form, but did not make the final cut. Many of these are included on the DVD edition as deleted scenes, including the Malfoys in Borgin and Burkes, several discussions about Harry being the heir of Slytherin, and the fight between Arthur Weasley and Lucius Malfoy in Flourish and Blotts.

The only significant deviation from the literary canon is in the effects of the Polyjuice Potion. In the book, the Potion causes the drinker to assume the exact appearance of the target, including their voice and any disabilities (such as poor eyesight). In the film adaptation, while the potion alters Harry and Ron's appearance, their voices were left unchanged to reduce confusion. This alteration is retconned in subsequent Harry Potter films – in Harry Potter and the Goblet of Fire Barty Crouch Jr, under the influence of the potion, perfectly assumes the voice of Alastor Moody.

A few characters were removed from the script and their lines reassigned to other characters. In particular, the ghost Professor Binns is absent from the film, so his expository scene about the Chamber of Secrets is instead given by Professor McGonnagall. Peeves is also absent from the film, as in all the other film adaptations.