The third — and, buzz has it, the best — of the Harry Potter (search) films opens Friday, but if you're not one of the tens of millions who have already seen the last two movies (or, better yet, read the books), you'll have to pull an all-nighter to catch up.
"The Prisoner of Azkaban" (search) fairly whizzes by, with nary a prologue, pause or flashback. If you don't know your Albus Dumbledore from your Argus Filch — well, "Azkaban" isn't going to explain it to you.
Happily, The Post will. Read on:
* The Dursleys: Uncle Vernon, Aunt Petunia and cousin Dudley are all that's left of Harry's family. Orphaned by the evil Voldemort (a.k.a. He Who Shall Not Be Named), who killed his parents and inflicted the jagged scar on his forehead, Harry (Daniel Radcliffe) is forced to spend his summers with this middle-class Muggle (nonmagical) family. Not only do the Dursleys treat him badly, but they despise harboring a wizard in their house, preferring to tell people that Harry attends St. Brutus' Secure Center for Incurably Criminal Boys.
* Hogwarts: The seven-year school of wizardry Harry really attends should not be confused with Hogsmeade, the magical town — with a surprising number of taverns — where Hogwarts students enjoy their parentally approved R&R.
* Hermione Granger and Ron Weasley: They're Harry's best friends at Hogwarts, though Hermione (Emma Watson) can get a bit bossy. Unlike Harry and Ron (Rupert Grint), Hermione is a "mudblood" — a derisive term for a wizard born of Muggle parents. And though Ron's dad is with the Ministry of Magic, the ragtag Weasley home is filled to bursting with red-haired children, including teenage twins Fred and George, as well as Hogwarts' insufferable Head Boy, Percy.
* Gryffindor: Students at Hogwarts are divided into four houses, and this one is for the best and brightest. Harry, Hermione and all the Weasleys are members of Gryffindor — as opposed to Ravenclaw, Hufflepuff and . . .
* Slytherin: Gryffindor's chief rival for supremacy is headed by the sinister Professor Snape (Alan Rickman), who seems to take a special dislike to Harry. (We won't find out why until book five.)
* Draco Malfoy: The platinum-haired gang leader of Slytherin is the son of Lucius, who is high up in the Ministry. Draco (Tom Felton) is a nasty twit, usually found in the company of his flunkies, aptly named Crabbe and Goyle.
* Albus Dumbledore: Hogwarts' kindly, all-knowing headmaster was originally played by Richard Harris (who died after filming the second installment). He's now played by Michael Gambon.
* Argus Filch: The school's oddball caretaker harbors an unhealthy fixation on his cat.
* Rubeus Hagrid: One of Harry's biggest fans is this giant (played by Robbie Coltrane) who loves all creatures — the fiercer, the better.
* The Fat Lady: A "living" portrait in the grand tradition, the Fat Lady won't let you past unless you know that night's password.
* Invisibility cloak: Passed down to Harry from his late father, James, it hides whomever (and whatever) stands within its folds.
* The Marauders' Map: Created by Harry's father (nicknamed Prongs) with fellow Gryffindor alumni Sirius Black (Padfoot), Remus Lupin (Moony) and Peter Pettigrew (Wormtail), the Marauder's Map shows the whereabouts of everyone at Hogwarts.
* Firebolt 2000: The ultimate flying broomstick is the dream of every Quidditch player.
* Quidditch: This high-flying sport involves blodgers, a golden snitch and — just see the damn movie!