Tyco Bass has been Chuck Masterson's and David Topman's closest friend ever since they built their space ship for a journey to the Mushroom Planet. Now Mr. Bass needs their help in a battle against time and the forces of evil that threaten the Mycetians, Mr. Bass himself and, finally, David.

Upon their arrival in the mountains of Wales for the Mycetian League meeting, Mr. Bass and the boys discover that the Necklace of Ta has been stolen. Also missing is the ancient Thirteenth Scroll, believed to relate the history of the Mycetians.

These must be found, for without the necklace, whose strange stones are carved in an unknown language, Mr. Bass cannot continue his efforts to translate the Scroll, the evil power that has hounded the Mycetians for centuries cannot be defeated.

Chuck and David use their wits as never before in a search which takes them from a joyous celebration to a terrifying test of endurance, all the while deepening their friendship with Mr. Bass.

From the dust jacket