When Harry comes around, he's back in the hospital wing (again).
He overhears Fudge and Snape talking.
Fudge says Snape will likely get an Order of Merlin award for his "heroics" in rescuing the kids from an escaped convict and a werewolf and a gang of Dementors.
Snape modestly says it was nothing. Which is somewhat true, at least – Snape didn't actually do anything at all.
He then explains that the kids were clearly under the influence of a Confundus charm, which means they were confused into attacking him.
Harry looks over and sees Hermione awake and listening like he is.
Ron is still out cold.
Harry and Hermione try to talk to Madame Pomfrey, but she just tells them to calm down.
Fudge and Snape come in and agitate Harry and Hermione further since neither man will listen to them.
Fudge is rather taken aback when Snape up and yells at Hermione.
Dumbledore finally arrives and shoos them all out so he can talk to Harry and Hermione.
Dumbledore says that he spoke with Sirius and that he believes him, but there's no proof and no time to prove Sirius's innocence before the Dementors perform the Kiss on him.
Dumbledore emphasizes the time part and Hermione picks up on something.
The headmaster then gives them very weird directions: he tells them exactly where Sirius is locked up, notes that they can save more than one innocent life, and warns them that they must not be seen. (Simple.)
Then he leaves and locks them in the infirmary.
Hermione whips out a tiny hourglass on a gold chain and throws part of the chain around Harry's neck. She turns it three times and everything blurs.
"He was standing next to Hermione in the deserted entrance hall and a stream of golden sunlight was falling across the paved floor from the open front doors" (21.96).
Hermione drags Harry into a storage room and drops a bombshell: they just traveled back in time courtesy of Hermione's Time-Turner, which she's been using to take extra classes all year.
Harry has hit his quota of startling revelations for the day.
But Hermione then admits that she doesn't get what Dumbledore wants them to do.
Harry figures it out, though: they need to rescue Buckbeak and use him to save Sirius.
So the two make a run for the forest.
They sneak over to Hagrid's house and watch themselves enter it.
"This is the weirdest thing we've ever done," Harry says (20.134).
Dr. Who, Marty McFly, Billy Pilgrim from Slaughterhouse-Five, and the casts of A Wrinkle in Time and Lost fervently agree with you, Harry.
Harry asks why they don't just run in there and kill Peter in his rat form after they found him in Hagrid's milk jar.
Writing that was probably the weirdest thing we've ever done.
Hermione says no way and explains that messing around with time is a bad, bad idea and that if he burst in there and his past self saw him, he's probably attack [...] himself. Our heads hurt.
Harry also experiences a time travel headache and says he gets the point, they'll let the evening play out like it already did.
Finally the window of opportunity arrives and Harry and Hermione untie Buckbeak and sneak him into the forest.
This time they hear what happens (happened?) after their other, past selves leave Hagrid's house.
Ow, ow, our brains.
At any rate, the adults are astonished to find Buckbeak gone and the executioner swings his axe into the fence in frustration.
Hey, that explains the noise the kids heard as they walked away from Hagrid's hut! There seems to be a time loop in play here.
So the adults all leave and Harry and Hermione then watch the odd spectacle of everyone heading into the passage to the Shrieking Shack.
They settle down in the woods to wait for everyone (and themselves) to come back out.
Harry is still upset that they can't rush in there and stop Peter and he tries to rush out, but Hermione grabs his robes and yanks him back just as a drunk Hagrid appears, heading towards the castle.
Close call there.
Harry agrees to sit and wait.
The two friends sit and talk. Harry explains what he saw when they were with the Dementors and confesses that he thinks his dad was the one who cast the Patronus.
Hermione doesn't see how that's possible, but Harry insists it looks like him.
Finally everyone emerges from the Shack and Harry wants to do something to stop Peter, but Hermione insists that they should just focus on saving Sirius, and Harry reluctantly agrees.
But then Harry realizes that werewolf Lupin is about to come rushing into the forest.
So he and Hermione drag Buckbeak and run to Hagrid's now-empty hut.
Harry then casually goes back outside to check out the situation.
He runs over to where the Dementors have gathered so he can hopefully catch his dad.
And he watches as they surround Hermione, and Sirius, and himself.
"And then it hit him – he understood. He hadn't seen his father – he has seen himself –" (21.295).
So Harry steps out and confidently casts a super powerful Patronus charm, which takes the form of a stag.
He rushes back to the hut to find a furious Hermione, but Harry explains what happened.
She's not sure what to be more shocked about: the fact that Harry saw himself and saved the day, or the fact that Harry cast some seriously advanced magic.
The two watch some more and then spy McNair the executioner leaving to get the Dementors.
So the two hop on Buckbeak and fly to the tower where Sirius is being held.
Hermione doesn't like flying.
Sirius is stunned to see them hovering outside his window. Hermione unlocks the window and Sirius climbs aboard Buckbeak.
Buckbeak lands on the castle and lets Harry and Hermione off.
Sirius tearfully thanks them and then flies off into the night.
Harry and Hermione watch until they can't see Sirius and Buckbeak anymore.