It’s a travesty that they didn’t even TRY to put this scene in the movie. It’s the most heart-wrenching scene of the whole book series—and deepens the motivation for everyone, not just Neville. And it makes it so much more satisfying when Neville is the one who “gets” the Room of Requirement, who improves so much in books 6 and 7.
(By the way, at the end of Book 5, Neville breaks the wand that belonged to his father in the battle in the Department of Mysteries. We are told in Book 6 that he and his grandmother get a new wand at Ollivander’s just before Ollivander disappears—and Neville is a much more talented wizard after that (though he had started getting better during DADA practice). The wand chooses the wizard. The wand Neville used wasn’t his, it was his father’s, and never was loyal to him.)
Order of the Phoenix, Chapter 23, Christmas on the Closed Ward:
The curtains had been drawn back from the two beds at the end of the ward and two visitors were walking back down the aisle between the beds: a formidable-looking old witch wearing a long green dress, a moth-eaten fox fur, and a pointed hat decorated with what was unmistakably a stuffed vulture and, trailing behind her looking thoroughly depressed — Neville.
With a sudden rush of understanding, Harry realized who the people in the end beds must be. He cast around wildly for some means of distracting the others so that Neville could leave the ward unnoticed and unquestioned, but Ron had looked up at the sound of the name “Longbottom” too, and before Harry could stop him had called, “Neville!”
Neville jumped and cowered as though a bullet had narrowly missed him.
“It’s us, Neville!” said Ron brightly, getting to his feet. “Have you seen? Lockhart’s here! Who’ve you been visiting?”
“Friends of yours, Neville, dear?” said Neville’s grandmother graciously, bearing down upon them all.
Neville looked as though he would rather be anywhere in the world but here. A dull purple flush was creeping up his plump face and he was not making eye contact with any of them.
“Ah, yes,” said his grandmother, looking closely at Harry and sticking out a shriveled, clawlike hand for him to shake. “Yes, yes, I know who you are, of course. Neville speaks most highly of you.”
“Er — thanks,” said Harry, shaking hands. Neville did not look at him, but stared at his own feet, the color deepening in his face all the while.
“And you two are clearly Weasleys,” Mrs. Longbottom continued, offering her hand regally to Ron and Ginny in turn. “Yes, I know your parents — not well, of course — but fine people, fine people… and you must be Hermione Granger?”
Hermione looked rather startled that Mrs. Longbottom knew her name, but shook hands all the same.
“Yes, Neville’s told me all about you. Helped him out of a few sticky spots, haven’t you? He’s a good boy,” she said, casting a sternly appraising look down her rather bony nose at Neville, “but he hasn’t got his father’s talent, I’m afraid to say...” And she jerked her head in the direction of the two beds at the end of the ward, so that the stuffed vulture on her hat trembled alarmingly.
“What?” said Ron, looking amazed (Harry wanted to stamp on Ron’s foot, but that sort of thing was much harder to bring off unnoticed when you were wearing jeans rather than robes). “Is that your dad down the end, Neville?”
“What’s this?” said Mrs. Longbottom sharply. “Haven’t you told your friends about your parents, Neville?” Neville took a deep breath, looked up at the ceiling, and shook his head. Harry could not remember ever feeling sorrier for anyone, but he could not think of any way of helping Neville out of the situation.
“Well, it’s nothing to be ashamed of!” said Mrs. Longbottom angrily. “You should be proud, Neville, proud! They didn’t give their health and their sanity so their only son would be ashamed of them, you know!”
“I’m not ashamed,” said Neville very faintly, still looking anywhere but at Harry and the others. Ron was now standing on tiptoe to look over at the inhabitants of the two beds.
“Well, you’ve got a funny way of showing it!” said Mrs. Longbottom. “My son and his wife,” she said, turning haughtily to Harry, Ron, Hermione, and Ginny, “were tortured into insanity by You-Know-Who’s followers.”
Hermione and Ginny both clapped their hands over their mouths. Ron stopped craning his neck to catch a glimpse of Neville’s parents and looked mortified.
“They were Aurors, you know, and very well respected within the Wizarding community,” Mrs. Longbottom went on. “Highly gifted, the pair of them. I — yes, Alice dear, what is it?”
Neville’s mother had come edging down the ward in her nightdress. She no longer had the plump, happy-looking face Harry had seen in Moody’s old photograph of the original Order of the Phoenix. Her face was thin and worn now, her eyes seemed overlarge, and her hair, which had turned white, was wispy and dead-looking. She did not seem to want to speak, or perhaps she was not able to, but she made timid motions toward Neville, holding something in her outstretched hand.
“Again?” said Mrs. Longbottom, sounding slightly weary. “Very well, Alice dear, very well — Neville, take it, whatever it is...”
But Neville had already stretched out his hand, into which his mother dropped an empty Droobles Blowing Gum wrapper.
“Very nice, dear,” said Neville’s grandmother in a falsely cheery voice, patting his mother on the shoulder. But Neville said quietly, “Thanks Mum.”
His mother tottered away, back up the ward, humming to herself. Neville looked around at the others, his expression defiant, as though daring them to laugh, but Harry did not think he’d ever found anything less funny in his life.
“Well, we’d better get back,” sighed Mrs. Longbottom, drawing on long green gloves. “Very nice to have met you all. Neville, put that wrapper in the bin, she must have given you enough of them to paper your bedroom by now.…”
But as they left, Harry was sure he saw Neville slip the wrapper into his pocket.
The door closed behind them.
“I never knew,” said Hermione, who looked tearful.
“Nor did I,” said Ron rather hoarsely.
“Nor me,” whispered Ginny.
They all looked at Harry.
“I did,” he said glumly. “Dumbledore told me but I promised I wouldn’t mention it…that’s what Bellatrix Lestrange got sent to Askaban for, using the Cruciatus Curse on Neville’s parents until they lost their minds.”
I become a weeping mess whenever I read this part. And it’s not in the movie at all—we see a headline in a news clipping and one line delivered by Neville directly to Harry, and that’s it. The movie completely robs the narrative of its emotional power.