In 1948, a group of miners finds a gallery full of emeralds in a salt mine in Switzerland, but they are attacked by giant black beetles and only one of them survives. In the present days, the explorer John Palmer is ready to take vacations in Greece with his family when he is contacted and invited by a stranger called Vincent to lead his team in an expedition into a mine in Switzerland. In return, Vincent offers a large amount to John and the cottage nearby a lake and the entrance of the mine for his family to spend the vacation. John accepts the offer, and while leading the group underground in the tunnels, he finds that their ambitious leader Marcel is a very dangerous man. When John meets giant black beetles in the cave, he orders the group to return but Marcel threatens the safety of his family, forcing John to lead the team to the deep location of the emerald mine.

Captain Saxon, and agent for the top secret Omega agency, has been given the assignment of tracking down and either capturing or killing the crew members of a secret space mission who returned to Earth against orders. It seems that they were all infected with an alien parasite, and they were trying to bring its eggs back to Earth. The eggs were lost in an accident, and both Saxon and the astronauts are trying to locate them. What could the government want them for?

In 1965, an American fighter squadron encountered a spaceship while flying over the Bermuda Triangle. After getting into a brief dogfight with it, one of the fighters is shot down, and the others agree to keep what they've seen a secret. Years later, the downed aircraft is recovered, and the son of the missing pilot insists on seeing it. Soon, strange ocurrences start happening around the son and his family. Could there be any connection with what his father witnessed?