For centuries, the Dropas' cocoons lay dormant until they were released from the ocean depths by a Soviet nuclear explosion. The aliens were integrated into society as slave labor but within a few years a deadly virus spread throughout the Western Territory killing millions of humans. The government blamed the contagion on spores from the Dropa cocoons. In response, a secret military squad known as the Legion was formed to exterminate the alien threat.Set in an alternate history communist America five years later, Dropa opens as Monroe, a former member of the Legion, is brutally murdered in a back alley outside a bar by a renegade Dropa named Mikhail. The best of the Legion's former trackers, Harrison, is forced out of retirement by The Party to eliminate the alien quickly and discretely. He begins his hunt by questioning Yelena, a bartender working the night of Monroe's murder. He discovers she is part of an underground resistance sympathetic to the Dropa and holds a vendetta against the government for the death of her parents. Yelena reveals Mikhail's whereabouts and that the Dropa had given her a message for Monroe, "There's a traitor among the Legion".Harrison follows up on Yelena's information with Mikhail's landlord Jin and soon begins to close in on his target. His search is aided with startling secrets about the Dropa from Arthur another member of the Legion. Arthur's revelations to Harrison and Mikhail's need for revenge lead both to a final battle that will peel back the secrets of Harrison's identity, merge his past and present and send him into a future that has become both clearer and cloudier at once. Harrison will be forced to decide how to exist in a world where fear is a weapon, lies are dressed as truth and entire populations are disposable.