Disclaimer: I own none of this, The HP universe and character was created by JKR.
"Here we come!" Hermione whispered.
She and Harry got to their feet. Buckbeak raised his head. They saw Lupin, Ron, and Pettigrew clambering awkwardly out of the hole in the roots. Then came Hermione… then the unconscious Snape, drifting weirdly upward. Next came Harry and Black. They all began to walk toward the castle.
Harry's heart was starting to beat very fast. He glanced up at the sky. Any moment now, that cloud was going to move aside and show the moon…
"Harry," Hermione muttered as though she knew exactly what he was thinking, "we've got to stay put. We mustn't be seen. There's nothing we can do…"
"So we're just going to let Pettigrew escape all over again…" said Harry quietly.
"How do you expect to find a rat in the dark?" snapped Hermione. "There's nothing we can do! We came back to help Sirius; we're not supposed to be doing anything else!"
"I have an idea, what is the summoning spell? Quick!"
The moon slid out from behind its cloud. They saw the tiny figures across the grounds stop. Then they saw movement —
"The incantation is Accio, but I'm not sure it works on humans or animals… There goes Lupin," Hermione whispered. "He's transforming."
"Accio Peter Pettigrew!" Harry yelled. About 10 seconds later a rat flew into his hands. Harry used the stunning spell on him. He has only read about the spell before and this was the first time he has ever used it, and he quickly realized how useful it could be, it is a fairly standard spell after all. Harry quickly picked up the rat and stuffed him into his pocket.
Hermione looked like she wanted to lecture him for altering the timeline but he put a stop to it quickly. He wasn't about to let his parents true betrayer just go, and leave his godfather potentially on the run any longer than he can help it.
"Hermione!" said Harry suddenly. "We've got to move!"
"We mustn't, I keep telling you —"
"Not to interfere! Lupin's going to run into the forest, right at us!"
"Quick!" she moaned, dashing to untie Buckbeak. "Quick! Where are we going to go? Where are we going to hide? The Dementors will be coming any moment —"
"Back to Hagrid's!" Harry said. "It's empty now — come on!"
"Right, it's nearly time," said Hermione tensely, looking at her watch. "We've got about forty-five minutes until Dumbledore locks the door to the hospital wing. We've got to rescue Sirius and get back into the ward before anybody realizes we're missing…"
They waited, watching the moving clouds reflected in the lake, while the bush next to them whispered in the breeze. Buckbeak, bored, was ferreting for worms again.
"Do you reckon he's up there yet?" said Harry, checking his watch. He looked up at the castle and began counting the windows to the right of the West Tower.
"Look!" Hermione whispered. "Who's that? Someone's coming back out of the castle!"
Harry stared through the darkness. The man was hurrying across the grounds, toward one of the entrances. Something shiny glinted in his belt.
"Macnair!" said Harry. "The executioner! He's gone to get the Dementors! This is it, Hermione —"
Hermione put her hands on Buckbeak's back and Harry gave her a leg up. Then he placed his foot on one of the lower branches of the bush and climbed up in front of her. He pulled Buckbeak's rope back over his neck and tied it to the other side of his collar like reins.
"Ready?" he whispered to Hermione. "You'd better hold on to me —"
He nudged Buckbeak's sides with his heels.
Buckbeak soared straight into the dark air. Harry gripped his flanks with his knees, feeling the great wings rising powerfully beneath them. Hermione was holding Harry very tight around the waist; he could hear her muttering, "Oh, no — I don't like this oh, I really don't like this —"
Harry urged Buckbeak forward. They were gliding quietly toward the upper floors of the castle… Harry pulled hard on the left-hand side of the rope, and Buckbeak turned. Harry was trying to count the windows flashing past —
"Whoa!" he said, pulling backward as hard as he could.
Buckbeak slowed down and they found themselves at a stop, unless you counted the fact that they kept rising up and down several feet as the Hippogriff beat his wings to remain airborne.
"He's there!" Harry said, spotting Sirius as they rose up beside the window. He reached out, and as Buckbeak's wings fell, was able to tap sharply on the glass.
Black looked up. Harry saw his jaw drop.
He leapt from his chair, hurried to the window and tried to open it, but it was locked.
"Stand back!" Hermione called to him, and she took out her wand, still gripping the back of Harry's robes with her left hand.
The window sprang open.
"How — how —?" said Black weakly, staring at the Hippogriff.
"Get on — there's not much time," said Harry, gripping Buckbeak firmly on either side of his sleek neck to hold him steady. "You've got to get out of here — the Dementors are coming — Macnair's gone to get them."
Black placed a hand on either side of the window frame and heaved his head and shoulders out of it. It was very lucky he was so thin. In seconds, he had managed to fling one leg over Buckbeak's back and pull himself onto the Hippogriff behind Hermione.
"Okay, Buckbeak, up!" said Harry, shaking the rope. "Up to the tower — come on."
The Hippogriff gave one sweep of its mighty wings and they were soaring upward again, high as the top of the West Tower. Buckbeak landed with a clatter on the battlements, and Harry and Hermione slid off him at once.
"Sirius, you'd better go, quick," Harry panted. "They'll reach Flitwick's office any moment, they'll find out you're gone."
Buckbeak pawed the ground, tossing his sharp head.
"What happened to the other boy? Ron?" croaked Sirius.
"He's going to be okay. He's still out of it, but Madam Pomfrey says she'll be able to make him better. Quick — go —"
But Black was still staring down at Harry.
"How can I ever thank —"
"There will be plenty of time later! I caught Pettigrew so hopefully we can get your name cleared soon, but first you got to get out of here!"
Sirius had a grin on his face at the thought of being free and was about to say something, but they looked impatient.
"GO!" Harry and Hermione shouted together.
Black wheeled Buckbeak around, facing the open sky.
"We'll see each other again," he said. "You are — truly your father's son, Harry…"
He squeezed Buckbeak's sides with his heels. Harry and Hermione jumped back as the enormous wings rose once more… The Hippogriff took off into the air… He and his rider became smaller and smaller as Harry gazed after them… then a cloud drifted across the moon… They were gone.
"I might just have a real home this summer…" Harry thought to himself. Things were looking up
Most of this chapter I took out right out of PoA- Hermiones Secret.