After Kes asks Paris to be her flight instructor, he finds himself falling for her. A jealous Neelix picks up on the Lieutenant's crush, and instigates a messy fight with Paris in the mess hall. Despite — or because of — the friction between them, Janeway decides to send the sparring pair on a shuttlecraft mission to replenish food supplies. The most likely source is a planet surrounded by trigemic vapors, which can cause severe skin irritation.
As they approach the planet, electromagnetic disturbances in the atmosphere cause the shuttlecraft to lose power, and they're forced to make an emergency landing on the planet. Tracking the shuttle, Voyager's crew notes their problems and launches a search-and-rescue mission.
In order to lessen their exposure to the dangerous vapors on the planet's surface, Neelix and Paris seek refuge in a cave and seal themselves in. Back on Voyager, search efforts are hampered by an attack from an alien vessel that places itself between Voyager and the planet. The crew is ultimately able to disable the alien ship's weapons systems and proceed to the planet.
In the cave, Paris and Neelix cautiously explore their environment. They find footprints leading to a clutch of eggs. As they watch, a reptohumanoid creature hatches from one of them. With the baby's mother nowhere in sight, Neelix decides that it's their responsibility to care for it. But when the baby's heartbeat begins to weaken, Paris realizes that by sealing the cave, they've cut off the supply of vapors the newborn needs to survive. Opening it up, they manage to get some of the nutrients from the air into the baby's system and it gets stronger.
Bonded by their concern for the creature, Paris and Neelix resolve their differences as they wait for the crew to find them. There is only a limited window of opportunity for Voyager to beam them aboard, but when, at last, the "window" opens and Voyager is able to contact the pair, Paris and Neelix delay beaming up for the sake of the baby. Soon, one of the aliens shows up on the scene; it seems to be the baby's mother. As Paris and Neelix watch, she retrieves the newborn. Satisfied, the Away Team returns to Voyager, where the two new friends go off to have a celebratory drink.