A decade in the future, humanity thrives in the absence of sickness and disease.
We owe our good health to a humble parasite - a genetically engineered tapeworm developed by the pioneering SymboGen Corporation.
When implanted, the tapeworm protects us from illness, boosts our immune system - even secretes designer drugs.
It's been successful beyond the scientists' wildest dreams.
Now, years on, almost every human being has a SymboGen tapeworm living within them. But these parasites are getting restless. They want their own lives . . . and will do anything to get them.