A distress signal is intercepted from a homeless alien species requesting safe harbour on planet Earth.
Government fixer Ernest C. Adler is assigned to negotiate the terms of their integration with a suspicious human race unwilling to shuffle up and make room.
As he works to sustain a peaceful but tense planet-share, a freak accident threatens to undo the delicate balance of power between human and alien.
Ramifications of the accident begin to reveal more and more about Earth's new tenants, and Adler faces a desperate struggle to prevent the two species turning on each other....