Back to Hogwarts Book 6 Harry Potter and the Half Blood Prince.

Book 6 Harry Potter and the half Blood Prince, To me is the best book and beginning of going back to Hogwarts. Harry is late getting off the Train after being attacked by Draco and left stunned under his Invisibility cloak. While in the Book it was Tonks who found Harry, Luna is the one who saves him in the Movie. This scene is where they arrive at the Gates to Hogwarts and see the Thestrals pulling the carriages with the other students.