Narrator: Beware, you may have just seconds to live. Some of the world's most dangerous encounters are closer than you think. Danger lurks in a long slumbering volcano near a major American city, and in a massive funnel cloud at your doorstep. It has highly toxic fangs and can even paralyze you with one nasty helmet to helmet hit. And don't forget to pull your chute. Now, Most Dangerous, on Modern Marvels.