A few days passed and each day the Dementors would come down and haunt Harry and Ginny, making them relieve their worst memories.
Harry's worst memories were his mother dying in front of him, facing Quirrell, finding Ginny nearly dead in the Chamber of the Secrets, being abused by the Dursleys. Ginny's worst memory was Tom Riddle speaking.
"We need to talk to Dumbledore." Hagrid said.
"Dumbledore?" Sirius scoffed. "I've been in here for twelve years and he hasn't helped yet."
"No, Hagrid is right." Harry said.
"Harry, how in the hell are we going to contact Dumbledore? We are here." Ginny said.
Harry smiled and got an idea.
"Ginny, come here. Look." Harry said, showing her the Invisibility Cloak and his wand. "We can escape."
"Look, Harry, I have tried to escape several times for twelve years. There is no way out of here." Sirius said.
"Did you have a wand?" Harry asked.
"Well… no, but…" Sirius began to say.
"Well, I have the Cloak. You said the Dementors are blind so they can only feel us. We know the Dementors take a break at 5 a.m., so that's when we'll strike. You can turn into a dog and me and Ginny can be under the Cloak." Harry said.
"What about Hagrid? We can't hide him under the Cloak. He's too, well, big. No offense or anything, Hagrid." Ginny said.
"None taken, Ginny." Hagrid said.
"Well, if we're gonna to escape, you need to know a particular spell. For the next 3 nights, we're going to do it. It's particularly difficult, it's a N.E.W.T.-level spell. It's the Patronus Charm. Expecto Patronum." Sirius said.
"Expecto Patronum." Harry repeated.
The next two nights, Harry tried to do it successfully. But failed.
"What happy memory did you choose?" Sirius asked.
"My first Quidditch match." Harry said.
"That's not good enough. Not nearly good enough." Sirius said.
Sirius then ordered Harry to try again.
"Expecto Patronum. Expecto Patronum!" Harry shouted and a bright blue stag appeared.
"Well done, Harry. What memory did you choose?" Sirius asked.
"When Hagrid told me I was a wizard and my reaction to leaving the Dursleys." Harry said.
Sirius smiled.
The next day, Ginny practiced and hers was a stag as well. Sirius was shocked as this meant that she loved Harry. Maybe Harry felt the same way.
The next day, Harry and Ginny put on the Invisibility Cloak.
"Bombarda." Harry whispered. The door broke open and Sirius approached them as a black, shaggy dog. Sirius transformed into a human and got under the cloak and opened the door silently. He turned Hagrid into a button and as they dived into the water, Hagrid was transfigured into a dragon. Sirius, Harry, and Ginny got on Hagrid, with the three (Sirius, Harry, and Ginny) still having the Cloak on. They then got to the shore and the spell wore off.
"Okay, we're going to need to Apparate. The Dementors probably just saw a Hungarian Horntail and assumed it was nothing." Sirius said.
"Harry, grab Ginny's hand. I'll grab Hagrid's hand." they obeyed Sirius' command and the four vanished with a pop sound.