You make your way down the hallway towards your friend's locker. Suddenly, a large group of students comes by on their way to Vista's after-school math club. You are distracted by their discussion about polynomials, coefficients, and greatest common factors. You have lost sight of your friend and you take a step backward to try to find him behind these mathematicians. 

Before you know what is happening, you have backed up against the mysterious door. You feel it open behind you as you stumble backwards.