The USS Enterprise-D proceeds through space when a distress call from Captain Lyrinda Halk of the USS Marco Polo, attacked by unknown assailants and near destruction. The Enterprise races to the scene, and Will Riker reveals Captain Halk is a childhood friend, with whom he shared an intimate relationship. The Enterprise is briefly waylaid by a super-string phenomenon -- long energetic gravity anomalies in their path. The crew then finds the Marco Polo adrift, and rescues Captain Halk and a few survivors, before the robot-controlled starships come about and chase the ships apart. The vessels, programmed by the long-dead Darzun civilization, are designed to attack anything within a certain radius from their fleet and home system. Riker, cut off aboard Marco Polo, leads the robot ships into the super-strings, where they are destroyed.