Once again, everyone but Harry gets to go to Hogsmeade for the holidays.
But this time, Potter has a plan.
He sneaks through the snow wearing his invisibility cloak, not realizing that it doesn't cloak his footprints in the snow.
George and Fred Weasley see Harry tromping through the snow and pull him aside.
They present him with the Marauder's Map, which shows the presence of everyone inside Hogwarts. It's like a magical paper version of Google Earth.
The map shows a secret route to Hogsmeade, which Harry takes.
If we had a secret passage to a village full of magical candy, well…it wouldn't be too long before we were too large to fit through the secret passage.