Enterprise is called to investigate strange occurrences on the, almost complete, Salem Three.  When major problems force an evacuation, not everyone returns safely to Enterprise.  Can the real saboteur be discovered in time to save the sector and its captive?

NEXT EPISODE: 5x13 - Phlox-In-Law  When Enterprise visits Denobula to pick up delegates for a trading conference, Phlox is not so pleasantly surprised by many familiar faces.  Meanwhile, T'Pol finds herself in an uncomfortable situation of her own.