Ships go belly up, high-rise towers burn, Mother Nature blows her volcanic top - all perfect settings for Irwin Allen to unleash his gift for putting star-studded casts in peril and audiences on the edges of their seats. Now the prolific producer plunges deep below terra firma into the rocky perils of Cave In! A handful of citizens (travelers, government officials, a park ranger) are trapped after the sudden collapse of the popular Five Mile Caverns. Someone else is with them: a desperate fugitive eager to claim a hostage after the group works its way to daylight. Slippery inclines, an underwater passage, a geothemal pit, a rickety bridge and more dangers stand between the group and blue skies. Hang on for adventure!