The twins Fred and George pull Harry back into the castle to give Harry their marauders map which shows all the secret entrances in and out of the castle.
Harry runs through the secret entrance to Hogsmeade with the invisibility cloak on so no one sees him sneaking out.
Harry, Ron, and Hermione walk into The Three Broomsticks.
Harry hanging out at Hogsmeade's bar with Hermione and Ron.
Harry's professors walk into the bar so Harry hides behind his stool which leads to harry overhearing Professor McGonagall, Hagrid, Fudge, and Madam Rosmerta talking about how Sirius Black was Harry's godfather and how he told Voldemort where Harry's parents are so he could kill.
Harry escapes back through the tunnel he came from with the invisibility cloak on.