Swarm Simon Afriel arrives as part of a two-year research mission to an alien planet inhabited by a race referred to only as the Swarm. Joining with another human researcher, Galina Mirny, the two explore the Swarm hive, which is composed of multiple castes of alien species that had been absorbed into the hive, each playing a specific role in maintaining the ecosystem. Simon reveals to Galina that his goal is to obtain and exploit the Swarm's genetic information, pairing it with artificial pheromones to create a new, more subservient swarm that will help humanity expand. Despite initial disapproval, Galina chooses to assist him as long as the nest remains unharmed. As time passes, the two become increasingly intimate. Their experiments, however, trigger a hostile response from the hive, which forcibly assimilates Galina. The Swarm speaks to Simon, explaining how the hive had absorbed intelligent species deemed as threats in the past and reduced them to symbiotic species. It tells Simon he can assist doing so with humans and retain his intelligence or be forcibly assimilated himself. He accepts the offer as a challenge, insisting that the human race will never become parasites.