A world with a toxic atmosphere where a previously unrecorded human colony settled on its southern continent in a self-contained biosphere as a genetically-balanced community some 200 years before its discovery by the U.S.S. Enterprise NCC-1701-D in 2368. The balance is forever changed when the starship helps ward off a neutron star's passing core fragment, which would have disrupted the planet's orbit and rendered the surface completely unstable.