En route back to Voyager, the shuttle carrying Paris and Torres is boarded by two unfamiliar alien lifeforms, who render the Voyager crewmembers unconscious and then leave. Voyager recovers the shuttle, but as the Doctor treats the badly injured Paris, he suffers from an increasing memory loss that he first encountered while running an opera program on the holodeck. Kes notices the Doctor's forgetfulness and alerts Torres to the problem. One easy solution would be to completely reinitialize the Doctor, but he would lose every memory of the past two years. In the meantime, Janeway's decision to stealthily pass through the territory claimed by a hive of insectoid beings may result in Voyager being destroyed by the aliens' sheer numbers.