This could have made for quite a fun adventure, had the casting not been so terribly wooden! Four folks in a diving bell find them selves stranded in a network of caves. With now ay back to their colleagues on the surface, they must try to find a way out through the caverns - where they encounter their own equivalent of "Ben Gunn" (Maurice Bernard) who has already been down there for fourteen years. Meantime, topside, "Prof Wyman" (John Carradine) desperately tries to find a way to rescue them - but with the diving bell lost, can he find a way? There is a heck of a lot of back-projection and p...