Throughout third year Harry had noticed that his friends were spying on him and that Hermione was trying to make him fail at school.
The story picks up just as Sirius and buck beak escape.

Just as Sirius was about to fly away Harry runs up and gives him a hug. While hugging him Harry whispers for Sirius to meet him at the leaky cauldron.
Harry and Hermione then run back to the hospital wing and make it just in time to get into bed before professor Snape and Dumbledore come in with the minister. They ate questioned about Sirius' escape but they can't prove anything.

A few days later Harry sends his aunt and uncle a letter saying that he will pay them if they cone and pick him up but drop him off at the Leaky Cauldron instead of taking him home. On the train Harry pretends that he needs to go to the toilet so that he can try and find Neville. Once Harry finds Neville's compartment he explains that Ron and Hermione have been spying on him and that he needs Neville's help. He then explains that Sirius is innocent and that he has plans to run away but needs to sort out a couple of things first.
Neville says "Harry I understand but I still don't get what this has to do with Me."
Harry shakes his head sadly as he replies "Neville you are more important then you know. The reason I'm telling you all of this is because I need help and you are the only one that I know won't ever willingly betray me. I'm going to get two boxes that will be connected so we can send each other mail and I'm also going to buy two multiple compartment trunks that can floo back and forth."
Neville takes in this information with a slack jaw before answering "I would be happy to help you Harry but why me? I can't do much. Do you realize that those things are going to be really expensive? If we do this you have to promise me that I can visit you or that you will visit me so I can see that you are alright."
Harry smiles and says "you are one of the bravest people I know so you are perfect to do this; also no one will suspect you. How about every Saturday we meet in the trunks at 9:00 PM so that no one knows what is going on and we can make sure the other person is okay? And yes I know that it will be expensive but I have the money and it's kind of easier than owls back and forth. Also you need to get your own wand, maybe you can display your dads, to convince your grandmother you could say that you don't want it accidentally broken or lost at school. Then you need to go to Gringotts and get a health check up and get then to remove any and all blocks also get them to do an inheritance test. After that get a goblin to direct you to a custom wand maker to get another wand."
"Why would I need that and how can I convince Gran to let me do all that? What is going to be in the multiple compartment trunks and how do I hide that from everyone? What if I can't do this? What if I fail? What if-"
"Neville calm down, I believe that you can do this or else I wouldn't have asked. The trunk will shrink to fit in your pocket so you can have your school stuff in your normal trunk. Tell your grandmother that you want to try and be a little bit independent to make your parents proud and then the next day ask to go to the alley by yourself, or to meet me. Just so you know I think that your parents would already be proud of you. For the trunks I'm going to make it so you go into one compartment and can then go through doors to get to the others, without getting out again. In yours there is going to be a greenhouse, a library, a room to experiment in, a practice room, a bathroom, a bedroom and a living room that will have the floo. Mine will have a potions lab, a library, a bathroom, a bedroom, a workout room, a muggle room, an experiment room and a living room with the floo. As for the custom wand it is always good to have a back up and it will fit better than your normal wand. I also want you to wear a pendant that I'm going to send you until you learn to close off your mind from people like professor Snape and Dumbledore. Also you are welcome to use the rooms in my trunk to practice potions and use the other stuff. The library will basically be the same except for books that you add after I give you the trunk."
"Thank you so much for trusting me Harry, I won't let you down. And you can use my rooms to. You had better go so that Ron and Hermione don't get worried that they lost you."
"Your right bye Neville see soon hopefully." after leaving Neville Harry went back to ron and Hermione and explained that he saw Neville and was wishing him a good holiday which is why he took so long. For the rest of the train ride the boys listened to Hermione worry about the homework they received and whether the boys would need her help or not. Once they saw Harry's relatives they said good bye and left. Harry hurried to the car and climbed in, only to have to explain that he had to get the money from the bank on his world before he could give it to them. They reluctantly agreed and drove him to where he needed to be. After a quick stop at the bank to get muggle money and then giving it to his relatives he booked a room and went to find Sirius so that they could go to the bank together.

As soon as they got to the bank they fired the account manager and did the tests to see if he had any blocks only to find that almost all his magic was blocked and all but part of his gifts were blocked, he also had a lot of compulsion spells and tracking spells on him. After unblocking all his magic he tried a spell and his wand burnt him, he was to powerful for it, his hair was also changing colors so they could see that he was a metamorphic so they tested his abilities again and the test showed that he was able to speak almost all languages and write them to, he could also understand and speak with sign language, he was metamorphic, he could talk to all animals, he had six familiars that could not find him until now, he also had the ability to learn other types of magic such as goblin and house elf, he was also going to be a multiple animagus he was also unlimited in his power. After his abilities were discovered they did an inheritance test and found that he was the heir to potter, black, emrys, Gryffindor, Ravenclaw and Slythrin though the last was by conquest.

After the tests they went to the leaky cauldron to sleep and talk through these new discoveries. After a dreamless sleep Harry and his dog went onto the muggle world to find a pay phone to call the one person that had always helped him and would most likely help him now. At the pay phone Harry pulled out a very worn piece of paper with a number written on it, he dialed this number and waited. After about thirty seconds there was an answer "Yeah Gibbs."