In the World of Tonantzin an epidemic is consuming the City of Calli, one of the two main cities of the planet. The authorities have decided that the only hope for the city is to use the magic powers of the green pearl. Nobody remembers the origins of the green pearl, but its beneficial powers have been known for many centuries.

In order to bring the pearl quickly to Calli, an expedition is organized to be lead by Captain Lamat, a man of great experience and strength. Due to the danger of this mission, for the land to be chartered is unknown, four people are carefully chosen for their special abilities to crew Captain Lamat's ship the Nautiflyius.

On its way to Calli, the Nautiflyius is pulled down by a strange force and crashes on the top of a tower in an area known only as the Forbidden Zone. While most of the crew is left behind to repair the craft, the Captain appoints one member to explore the tower and find fuel for the craft.

Where are they? Can they fix the craft and get on with their mission? And what are those strange noises coming from the tower?