Technician Delia Alitce is new to Interstellar Observation and Navigation, but her role as caretaker of the Herschel Beacon is critical for guiding ships through the dense cloud of the Cat's Eye Nebula. Her only companion on board the beacon is the disembodied voice of the station's artificial intelligence. But when things start to go bump in the night, Delia may find that space is not as empty as she had thought.