The USS Tokyo responds to a distress call from the Alvatar Colony along the Romulan Neutral Zone. On arrival at the colony the crew of the Tokyo discover that not only has the colony's starbase being destroyed and a new mysterious base now hangs in orbit, but much of the colony was heavily damaged, and many of the colonists have now disappeared.

When an away team beams over to the mysterious starbase, they discover something truly shocking. Every single colonist is now being held in strange alien type pods in some sort of stasis.

However all the male colonists are being transformed into strange alien creatures, whilst the female colonists seem to have been impregnated with the same creatures against their will! Some of them showing evidence of having given birth and now being transformed into the same alien creatures!

What will happen when a powerful warship returns to the starbase and disables the Tokyo? Will the crew of the Tokyo suffer the same fate? What happens when the Romulans also show up?