A trader named Gar brings the Doctor's mobile emitter to a crowded hospital where he barters a price for the "trinket" with Administrator Chellick. The emitter is activated and the Doctor vehemently protests his kidnapping. However, when injured patients arrive, the Doctor puts his emotions aside in order to treat them.
Back on VoyagerHarry and Tom discover that the Doctor was kidnapped after they visit sickbay and find a cheap imitation in his place. Voyager begins to try and locate the Doctor.
Meanwhile on the medical ship the Doctor discovers a miner named Tebbis has a terminal condition that could easily be treated by cytoglobin, but has not been. When he asks a fellow doctor, why Tebbis hasn't been treated he is told that Tebbis doesn't have a high enough Treatment Coefficient (TC), calculated by a complex algorithm that measures their benefit to society.
Chellick returns and tells the Doctor that the main computer, known as the allocator, has decided he would be better utilized on Level Blue, where patients with the highest TCs are kept. On Level Blue conditions are vastly superior. The Doctor learns that this is because a person's TC determines the quality of treatment they get. Moreover, Level Blue patients receive prophylactic care before lower-level patients receive emergency care.
On Level Blue, the Doctor tells a nurse that a patient requires an additional cytoglobin shot which he takes to Tebbis. With his help medicine is distributed to other patients with low TCs. While conversing with Tebbis, the Doctor discovers the TC is just a single facet of a stratified -- maybe even caste-bound -- society. Chellick discovers the Doctor's scheme and has the Doctor restricted to Level Blue.
Voyager finds Gar's ship and has him beamed to the brig. There, Neelix feeds Gar a meal made with Talaxian wormroot, telling Gar afterwards it could give him painful abdominal spasms. He says that without the Doctor, they can't be treated. Gar quickly tells Neelix where the Doctor is and Voyager sets off to get him.
Meanwhile, the Doctor learns that Tebbis has died and he manages to escape Level Blue so he can continue to help low TC patients. When Chellick finds the Doctor he attempts to de-activate him but the Doctor injects Chellick with blood from Tebbis, turning him into a low TC patient. With a low TC, Chellick can only be given cytoglobin by moving all low TC patients to Level Blue where they will all be treated. Chellick does this as Voyager rescues the Doctor.
Back on the ship the Doctor asks Seven of Nine to perform a scan on his ethical subroutines as he thought deliberately infecting Chellick might be a sign they were malfunctioning. Seven tells him Borg philosophy states that the loss of one for the greater good is worth the sacrifice; she then declares that his ethical subroutines are in perfect order.