Harry Potter (Radcliffe) has not had a good summer. Not only has he had to put up with his overbearing Aunt Petunia (Shaw) and Uncle Vernon Dursley (Griffiths) and their dread of his magical abilities, but it seems as if Harry’s best friends Ron Weasley (Grint) and Hermione Granger (Watson) have forgotten him as they haven’t replied to a single one of his letters. Then, suddenly and mysteriously, house-elf Dobby appears in Harry’s bedroom and warns him of great danger if he should attempt to return to Hogwarts School of Witchcraft and Wizardry.

Dobby is so eager to prevent the young Gryffindor from returning to Hogwarts, he has blocked all of Ron and Hermione’s correspondence from reaching Harry. But despite the elf’s mischievous efforts, the ever-determined Harry is rescued from the Dursleys’ dreary clutches by Ron and his brothers – with the aid of a flying car! – and whisked into the warmth of the Weasley household.

But when Harry and Ron are suspiciously prevented from entering Platform 9 æ and boarding the Hogwarts Express back to school, the boys take emergency action to avoid being late for the new term – only to incur the wrath of Professor Snape (Rickman), who calls for their expulsion after they crash the flying Ford Anglia into Hogwarts’ enchanted Whomping Willow tree.

Meanwhile, news of Harry’s first year heroism has spread throughout Hogwarts and he finds himself the center of much unwanted attention. His new fans include Ron’s little sister Ginny (Wright); first year would-be photographer Colin Creevey (Mitchell); and most irritatingly, the new Defense Against the Dark Arts Professor, Gilderoy Lockhart (Branagh).

Outshone only by his own vanity, Lockhart craves the attention that Harry shuns and is all too willing to associate himself with Hogwarts’ young hero. But not even Lockhart can offer an explanation for the sinister new terror that is gripping the school.

Now all eyes are on Harry, and his friends are beginning to doubt him. Everyone, that is, except Ron, Hermione and fragile young Ginny, whose focus has turned to her mysterious new diary.

But Harry is not about to let his friends down and, with or without the support of Gilderoy Lockhart, he will confront the dark force lurking in his beloved school.