Synopsis: Doors (Preliminary title and subject until something better comes along)

Still trying to decide what I'm going to write, but I for now I'm going with ...

"Doors," or portals, appear all over the world in different places. Some people are drawn to go through them - when they enter, they disappear. We call them seekers, although the don't appear to consciously decide to go, they just find themselves going. Nobody has the power to stop them. Barricades, soldiers, guns - nothing can stand in the way between the seekers and the doors. Do the doors work both ways? Will the seekers return? Will something else come out?