While searching for dilithium on a planet surface, an alien attacks Neelix and electronically removes his lungs. After the Doctor manages to stabilize him, the Voyager chases the aliens through several star systems in hopes of retrieving the stolen organs needed to save Neelix's life.
Neelix will die within an hour if the Doctor doesn't get the lungs back. Unfortunately, the crew will not likely catch the aliens by then, who have a head start and a ship just as fast as Voyager. This leads the Doctor to execute an "unprecedented medical procedure" by creating holographic lungs for Neelix to use. The drawback is that Neelix must remain in a restraining field because the computer cannot compensate for movement.
This is a much more promising Voyager outing, with some good character moments and a plot less dependent on technobabble and Trek cliches. Finally we gets some healthy characterization, as well as a plot that offers a threat without excessive jeopardy. It's nothing brand new (which the series has the potential for), but it does work.
Placing Neelix in the restraint leads to a number of humorous yet understandable moments. He feels paranoid and alone, believing that his paralysis gives Paris the chance to go after Kes. Unexpectedly funny dialog includes Neelix labeling Paris a vulture who is merely "one big hormone walking around the ship."
The banter between Neelix and the Doctor is adeptly conceived and performed. Picardo once again successfully pulls off the character of the disgruntled doctor, with his annoyed personality remaining simultaneously within the boundaries of mild comedy and plausibility. Picardo's line, "I'm a doctor, not an interior decorator," is a scream.
The scenes with Kes also work well. Kes comes across much better here than in "Time and Again," in which she came across as, frankly, annoying. Here she is supportive of Neelix and her optimism proves helpful. Scenes between Kes and the Doctor are engaging and likable.
Meanwhile, Janeway chases the alien organ thieves into an artificial asteroid that reflects sensor information. This causes a "hall of mirrors" effect that hides the alien ship while creating a million false images of the Voyager. Tuvok's idea to bounce the ship's phasers off the walls like a searchlight is strangely amusing.
Capturing the aliens leads the crew to discover why the aliens stole the organs. They are a race of beings whose existence consists solely of fighting the "phage"—a disease that destroys their bodies and breaks down their organs. The race's advances in medical technology are the only thing keeping them from extinction. They harvest organs to save their own lives.
The two aliens reveal that Neelix's stolen lungs have already been transplanted into one of them. Returning Neelix's lungs would mean the alien's death. This gives Janeway a judgment call which is handled with a reasonable amount of dramatic power (though Janeway nearly getting misty-eyed was pushing it). She cannot justify killing the alien to retrieve Neelix's lungs, but gives them a forceful warning that any violent intentions in the future would be met with "the deadliest force."
In exchange for saving his life, one of the aliens agrees to use their superior medical technology to perform a tricky lung transplant in which Kes donates one of her lungs to Neelix.
In addition to introducing a new alien race, another thing "Phage" does is give Kes a job on the ship. Though it seemed like Kes was headed toward possibly being a character with no purpose, the episode remedies this situation when the Doctor recruits her as his assistant. (This should come as a relief to "temporary field doctor" Paris.)
Perhaps it doesn't have audacious plotting, but "Phage" is a good, solid episode of science fiction that continues to flesh out the characters.