From what I understand, that's the same thing as a wormhole. If you imagine spacetime as a curved two-dimensional surface (like the surface of a soccer ball), then you would have to travel from point A to point B on any part of that surface in a curved line at, maximally, the speed of light.
But if you should somehow be able to open a path that allows you to travel "under" the surface, in an area of nonspacetime, then you could (theoretically) get from A to B much faster, even instantaneously, as long as there was an opening at both points to travel through. If you imagine that space connected by a tube, that's the Einstein-Rosen Bridge.
That type of wormhole is very unstable. It would only allow FTL travel if it could be kept open long enough to allow a particle to traverse it. To keep it open long enough to allow a particle to traverse it, you'd need exotic matter to sort of "hold its throat open." Unless of course there is no "time" that it takes a particle of light to traverse the wormhole. I think there may be a lot of theories about speed of light travel through the wormhole itself, though.
Please note that this model of a wormhole, based on 2D space with a 3D bridge, is just a way to describe something that can't be really visualized. In actuality, spacetime is three dimensional, and the only way through would be to pen another (theoretical) dimension.