On Monday morning, Harry was in the library looking through a book called Wonderous Winged World, a bestiary by Sally Soar first published in 1414.

Wonderous Winged World highlighted creatures who possessed the power of flight. As such, Harry figured it might have some useful information on hippogriffs that could help Buckbeak in his trial.

But something in the introduction caught Harry's eyes and brain.

This something probably wouldn't be relevant to Buckbeak, but Harry had an immediate gut feeling that it was extremely important.

There was a section in the introduction about animagi and one particular tidbit caught Harry's eye the nanosecond he read it.

According to Sally Soar:

"Any magical material, object, or artifact that has been created or bewitched to reveal the presence of humans in any confined area can also be used to discover unregistered animagi. This is accomplished by pointing one's wand at the material, object, or artifact in question and saying the incantation "Animagus Reivilo!" After the spell is performed, the animagus's animal form will be stated below his or her name. For example, if a witch named Karen Kitty took the form a cat, then on any material, object, or artifact that showed where humans were present in a confined area, the word "cat" would appear below the name Karen Kitty."

Harry had a feeling that he'd just learned something very important.

"OOH!" Harry realized suddenly.

Tucking Wonderous Winged World under his arms, Harry darted back up to his dorm in Gryffindor Tower.

To Harry's relief, Ron, Neville, Dean, and Seamus had all left the dorm and it was empty.

Harry therefore retrieved the Marauder's Map from his trunk.

Harry pointed his wand at the map and said, "I solemnly swear that I am up to no good."

The map activated and before he could even think about revealing animagi, he noticed the weirdest of the weird.

In Hagrid's Hut, a now stationary dot stated that Peter Pettigrew was sleeping.

Pettigrew was supposed to be dead. How could he be showing up here?

Harry had a sudden suspicion and now performed the incantation "Animagus Reivilo!"

Next nanosecond, Harry sat frozen still at what the spell and map had just revealed.

Below the name Peter Pettigrew was now the word rat.

And that wasn't all.

As Harry's eyes scanned the map further, he saw a dot in the Forbidden Forest labeled Sirius Black that stated Sirius was also sleeping, Below the name Sirius Black was the word dog.

Harry retrieved a bottle of Budweiser from his trunk and took a few sips thinking "This is BIG!"

Harry took a few more minutes and a few more nanoseconds to ponder what this all might mean when a reality hit him suddenly.