Below the English town of Ipswich a tunnel boring team is digging through solid rock when unexpectedly, they break into an ancient cave system filled with animal bones. Strangely, there were also the remains of men, knights in armour, some crushed, and some seemed to have had their bones and flesh melted. And there was one more thing found - a huge, egg-shaped ruby that glowed like a setting sun.

Just over 2000 miles away, still trapped on the lost island of Lemuria, Troy and Anne know that the time of monstrous beings long thought only existing in our legends or lurking in our nightmares, was returning.

But they now have a chance of escape - they have found the fabled submarine, the Nautilus. Together, Troy, Anne, the secretive Elle and the huge Viking woman, Yrsa, work together to break free so they can warn the world of the terror that is coming.