Synopsis
In the A-story, Dr. Franklin investigates an alien healing machine being used by a physician in Downbelow. A murderer is convicted and sentenced to the "death of personality."
The B-story has Londo being told by one of the Centauri senators to make more efforts with other species, as their support may be useful. Shortly after this he meets Lennier, and offers to show him more details of Babylon 5.
A resident of the station, Mueller, is found guilty of three murders and is sentenced to "death of personality", an alternative to capital punishment in 2250s Earth Alliance which involves "brain wiping" the condemned's existing personality and replacing it with one programmed to serve the community for the rest of his natural life.
Ivanova finds Franklin is running an unauthorized free clinic in Downbelow. She is sympathetic to Franklin's cause. However, Franklin in turn hears of rumors of another clinic being run there and investigates. He finds Laura Rosen using an alien machine that allegedly cures humans—and possibly aliens, though this is not disclosed in the show, just implied because of its alien origin. Franklin talks to her daughter, Janice, and finds her mother was a doctor, before she made an error due to a stims habit. She then went in search of alien medical technology to make amends and found this device.
Londo has taken Lennier to a club with exotic dancers, and narrowly avoids giving Lennier an alcoholic drink, which reacts badly with the Minbari physiology. Londo is rather bored of Lennier's talk, until he mentions he studied probability. Londo suggests they tests his skills with a game called "POK'ah."
Talia scans the prisoner Mueller and finds not three but dozens of murders he committed. She is overwhelmed by the events and has to break contact.
Lennier appears to be quite good at poker, but fails to grasp the subtleties of the game, meaning he is only winning modest amounts rather than large amounts.
Franklin investigates further and finds the machine takes life energy from one person and gives it to another. He tells her the machine is gradually killing her. Dr. Rosen says she is aware of this, but she has a highly painful and degenerative condition and has little time to live anyway. She agrees to give Franklin the machine in the event of her death.
Back at the gaming table, it appears Londo is using some parts of his anatomy (later revealed to be one of his six tentacle penises) to switch cards, much against the rules of poker (and decency). When discovered, this causes a fight to break out.
Mueller has escaped from his captors and heads for Downbelow. He is shot in the escape, and heads for Rosen's clinic, where he holes up and takes Rosen and Janice hostage. Franklin later shows up and becomes a hostage himself. He forces Rosen to treat him with the alien device, but instead she reverses the device to drain his life energy. She remarks to this cold-blooded killer that he is experiencing in a few agonizing seconds the condition she bore for several years. This process kills Mueller.
Dr. Rosen is brought before a magistrate which clears her of any criminal charge due to acting in self-defense, albeit with the additional order to surrender the healing machine to station personnel. However, she feels morally unwell at having taken a life to extend her own—even if that life belonged to an irredeemable mass murderer threatening herself and her daughter.
Commander Sinclair confronts Lennier and Londo, Lennier takes the blame, and both are excused because of diplomatic immunity, although they are convinced to financially compensate for the damage caused. Lennier discovers the true nature of Londo's appendages, and Londo learns a little about Minbari culture: that honesty is valued, but that one may lie to save face for another.
Read more about this topic: The Quality Of Mercy (Babylon 5)