Synopsis

Harry Potter returns to Hogwarts for his third year, where rumors spread that escaped prisoner Sirius Black is hunting him. As Dementors haunt the school grounds and strange events surround the mysterious Professor Lupin, Harry learns that the danger may be connected to his family's past. With Ron and Hermione's help, he uncovers a long-hidden betrayal and confronts the truth behind Sirius' escape.

Factoids & Trivia

• Principal photography took place from February 24 to November 28, 2003, at Leavesden Film Studios and became the series' first installment to make extensive use of real locations. Scotland, Oxford, London, and Virginia Water in Surrey all appear in the finished film.

• The Knight Bus sequence was designed to look impossibly fast without actually driving at that speed. The bus traveled at about 30 mph while surrounding vehicles moved at roughly 8 mph, with carefully choreographed pedestrians and stunt drivers helping sell the effect.

• The filmmakers initially experimented with underwater puppets to determine how the Dementors might move. Although the puppets were not used in the final shots, the slow-motion tests influenced their floating, fabric-like visual style.

• Buckbeak combined practical creature work with computer-generated imagery. The visual-effects team began with a skeletal study so that the hippogriff's wings, feathers, and limbs would move believably.

• Aunt Marge's inflation was achieved with practical prosthetics rather than a fully digital effect. The production used 38 tweed suits in progressively larger sizes, while the largest costume weighed about 50 pounds.

• The Hogwarts exterior miniature was expanded by approximately 40 percent for this film. New additions included a clock tower, courtyard, hospital wing, and other architectural details that made the school grounds feel more extensive.

• John Williams returned for his third and final score in the series. The soundtrack introduced a more somber musical approach, including "Double Trouble," a choir piece whose lyrics draw on Shakespeare's Macbeth.

• The film won the 2004 BAFTA Orange Film of the Year public vote and received Academy Award nominations for its original music and visual effects.