Really, really cool behind-the-scenes information about the production of the Harry Potter movies. I learned so much about the Harry Potter universe, the actors, and the way movies are made. Like the fact that Mafalda Hopkirk was played by Sophie Thompson, the younger sister of Emma Thompson, and Bill Weasley was played by Brendan Gleeson's son Domhnall. And that the prop crew bought sixteen Ford Anglias from around the country to use in filming. That most of the amazing props and sets were really physically made, with animatronics to make them move—like the Whomping Willow, the doors to the Chamber of Secrets, Aragog, the basilisk's head and 25 feet of its body, etc. The wizard's chess scene was done entirely in real life—the only effects they added digitally were some extra dust and debris for the explosions. They built those giant pieces and actually blew them up on-set.
Hagrid and Madame Maxime were played half the time by very tall doubles wearing massive prosthetic heads. In the graveyard scene at the end of Goblet of Fire, when they were doing the shots that showed only Harry, Ralph Fiennes would stand near the cameras yelling insults at Daniel Radcliffe to help him keep up the emotion he needed for the scene. Evanna Lynch—the girl who played Luna Lovegood—was a Harry Potter fan before she auditioned for the movie, and when Jo Rowling found out she'd been cast, she remembered that Evanna had once written her a letter, and the two had corresponded. Matt Lewis (Neville) wore a fat suit, false teeth, and plastic behind his ears for all the movies except the last one. Emma Watson had a crush on Tom Felton in the earlier movies, and it was one of those embarrassing kid crushes where everyone on the whole set knew. For Goblet of Fire, director Mike Newell had James and Oliver Phelps practice fighting each other. They weren't getting it, so he had one of them volunteer to fight him, and they wrestled until Newell cracked a rib. The Knight Bus was an actual double-decker bus painted purple with a third layer welded on top of it.
The outfits that Ron, Hermione, and Harry wear in Prisoner of Azkaban are almost identical to the ones they wear in Deathly Hallows, because the costume designer wanted them to have recognizable looks throughout the series. Ron's always in oranges, reds, and greens, because those are the homemade Weasley colors; Hermione wears pinks and greys; and Harry wears blues and greys and muted colors because he's always been an outcast and is used to wanting to blend in. In Order of the Phoenix Umbridge's clothes get pinker and pinker as she becomes more and more sinister (and Imelda Staunton requested that her outfits be designed to emphasize her rear, so she could develop a distinctive walk, which I thought was funny). Voldemort started out wearing a very thin layer of silk, and as each movie goes on and his power becomes more and more solidified, they added layers on. And the scenes with Polyjuice Potion are so fun to think about—Emma Watson acted the scenes, and then Helena Bonham-Carter imitated her. Daniel Radcliffe had to do the same thing with all six of the actors who played Hermione, Ron, Fred, George, Fleur, and Mundungus in the scene with the seven Potters.
That's just the stuff I can remember off the top of my head right now. It's an enormous book, and you wouldn't think you'd actually sit down and read it—but it's definitely interesting enough to do so.