Mike and Eddie Hunter's construction company is hired to bore a road tunnel through Giant's Tooth, a mountain in the French Alps. As they complete the tunnel they are attacked by beasts, who turn out to be Emile LaTour's tunnel crew from a century before. The beasts save the Hunters' crew from being transformed into beasts and are retrapped in a tunnel cave-in.; Ellen Ward's cousin concocts an elaborate scheme posing as aliens in an attempt to claim her inheritance from a deceased uncle, but Jack Ward figures out the hoax and captures Ellen's cousin and his gang.; Roger Steele is given a diamond by an unnamed man and told it has a curse that may doom him. He is unable to throw it away without it returning but it is finally stolen and the thief is killed by it.