I realized that I have very little ability to develop any of my ideas without bouncing things off of other creative people. And since I only do that for a select few of my ideas, I love that I can just throw the rest into the internet for whoever wants them...our one follower...
Twin girls get arrested in a Soviet Union type government for being non-conformists. People in the prison begin to disappear (guards, prisoners, etc...), until just the twins are left. Then you discover the twins are the leaders of the rebellion and had tunnels made for years to every cell and area in the prison, and every person taken has been liberated to join their forces. The prison is turned into their fortress, for their attack on the palace.
It would be neat if this seemed like a horror for the first half, and then like a revolution for the second.