Voyager is struck by a forceful energy field which does little damage and deposits information in the ship's computer. Janeway decides to investigate the source of the energy wave, finding a badly damaged ship with a curious, non-humanoid life form aboard. The creature attaches itself to B'elanna, nearly killing her in the process, and the Doctor is unable to remove the creature without destroying its victim. The Doctor creates a hologram of famed Cardassian exobiologist Krell Mocet to assist in the desperate fight to save B'elanna, but both B'elanna and a young Bajoran crewmember remember Mocet for his war atrocities during the Bajoran occupation. Making matters worse, the slowly dying B'elanna forbids the Doctor to allow Mocet's assistance in a surgery that could save her life. The question of whether a former torturer's research should be used to save one crewmember soon divides the crew.
