Some time ago, months, maybe even years, you came upon a mask. It might not have looked all that special, or maybe it did, but you took the mask home with you. As with many things, you decided to mess around with it. You put it on, and you become another person. You're physical attributes might have changed, you could be smarter, have powers that were explainable, even with modern science.

You decide to use the mask, creating an alias for yourself, using the powers to stop crime, or maybe help and cause it. 

Now, the last few times you took off the mask, you've felt almost a drag of some sort. The reversion to your old self isn't happened instantly like it used to. Your powers are still usable for a few minutes after you take the mask off, and you even have a few lingering thoughts in the mindset of your alter-ego.

You put the mask on again, and you suddenly have the need to go somewhere. A feeling in the back of your head that is pulling you to a specific area, bu you don't know where. After fighting the feeling, you eventually follow it. it could have been a block away, or even another continent. You arrive at a building in the middle of nowhere, grass and dirt for miles in every direction. You go into the building, see what's going on.

You find others with masks.