Jewels of Elsewhen

You are riding home from work on the subway. There is a jolt - and as you fall against your neighbour you discover - he is a manikin.
You investigate. The entire train is filled with manikins. Are there no humans in this world...?
You approach a door. There is only an opaque blackness on the other side. You are wary. You put through only one arm. It disappears completely. You are curious. You must ...