Plot summary
Voyager encounters a distress call and finds a ship with a non-humanoid life form on the verge of dying. They transport the scorpion-like creature to Sickbay but it wraps around B'Elanna Torres, creating a physical and biochemical bond. Doing nothing means Torres will die; separating them risks killing them both. The Doctor programs the holodeck to recreate the brilliant Cardassian exobiologist Crell Moset to help.
A Bajoran ensign reveals that Moset made advances in medical research by experimenting on Bajorans during the Cardassian occupation of Bajor. Torres, a former Maquis member, refuses to accept any procedure developed by the Cardassian hologram. Moset discovers a procedure to separate the creature from Torres without harming either; in order to save Torres, Captain Janeway orders the Doctor to proceed despite her wishes.
The Doctor and Moset begin the operation in the holodeck. A ship carrying other scorpion-like aliens arrives and holds Voyager with a tractor beam. The holodeck loses power, putting the operation at risk. Janeway insists on a peaceful solution and refuses to counter attack. First Officer Chakotay reroutes power to the holodeck, allowing the Doctor and Moset to complete the operation. Janeway has the creature transported back aboard the new ship; the ship leaves.
Torres is furious at Janeway for overriding her wishes. The Doctor faces a moral dilemma regarding the Moset program. Moset argues that although his medical knowledge was obtained unethically, it could benefit humanity; furthermore, since the Doctor has already used the unethically obtained knowledge to save someone, the Doctor is no better than he. The Doctor cannot in good conscience continue using the Moset program and its knowledge, and orders it deleted from the computer.
Credits
Adapted from Wikipedia contributors, Nothing Human. Paragraphs and formatting adjusted; illustrations, reference markers, block quotations and non-story material omitted.