Gemworld is a world unique in the Federation and throughout known space. The surface is an intricate, multi-plane construct made of growing crystal fueled by matter gathered from its inner core and outer space. It is a beautiful, low-gravity world peacefully inhabited by the myriad species who design and maintain the crystal growth. Now it is dying - poisoned from within by an unknown saboteur - and the Enterprise is trapped there by a deadly singularity created by the 'poison pill.'
To save Gemworld, the Enterprise must disable the artificial shell which holds the planet' s atmosphere intact. But to safeguard the shell - since the planet could not survive without it - it cannot be shut down without six clearance keys. One key is in the possession of each of the planets distinct and often reclusive species, and travel on the crumbling planet is nearly impossible. A powerful sect views the shell as a holy object and will stop Picard from tampering with it - at any cost. When the keys are gathered and a mysterious murder is solved, the responsible party is discovered to be the planet itself!