In Volcano Under the City, NOVA researchers take a sojourn to Mt. Nyiragongo, Congo, in West Africa, a volcanic crater that suddenly exploded in January 2002. Lava engulfed much of the neighboring village of Goma, some 100 miles distant, killing 100 people and destroying the homes of 120,000. In the years since, research scientists (and villagers) have become terrified that volcanic activity of greater severity will transpire beneath the city, bringing the entire community to a tragic and gruesome end. To grasp the nature of the volcanic activity -- and how it might ultimately be prevented -- NOVA thus sends a group of scientists, including French volcano expert Jacques Durieux and Italian geologists Orlando Vaselli and Dario Tedesco, to camp out on one of the inner rims of the volcano, where they begin to conduct research experiments that will lead to a greater understanding of seismic catastrophe and may help prevent related environmental tragedies such as the associated discharge of lethal carbon monoxide gases throughout the surrounding atmosphere.