In the 22nd century, Dr Abigail Darius is a physicist investigating the possibility of membrane universes. When her funding is cut off, her husband, Dr Mike Fitzroy, finds a way to allow her to continue her investigations using a DIY rig in their basement. She finds the universes, but everything changes when someone replies to her message.

The humans on the other Earth are mere shadows, waiting to die, and the suggestion is made that people from our Earth move over there to replace them. But how? Is it safe? What about the people already there? How do you decide who would make good candidates to start again on another world?