You play as Harry
Long story short, Harry never got to go to Hogwarts. The Dursley's didn't let him go, nor has he for the past 5 years because they found all sorts of ways from keeping him from going.
However, just because they kept him from attending doesn't mean that weird and strange stuff didn't stop happening around Harry. Last week, he actually set his homework on fire when he couldn't figure out a problem.
Today is his birthday. The Dursleys decided to go to the mall to get Duglly a new video game, and Harry had to come too. Yippy. However, what they didn't know is that Hogwarts was having a field trip to that mall to see the muggal world, and they noticed Harry and the Dursleys.
They pointed and whispered "is that him?" And "look at his scar!". The Dursleys were not too pleased about that, and tried to move Harry away from the students' and teachers' sight. Until a confident student with bolnd hair and a black robe and green tie came over and asked who you were.
"Hello. I'm Malfoy. Draco Malfoy. And who are you?"