Guardian of Forever

This book - Guardian of Forever - is a science fiction explanation of the "Curse of the Pharaohs." It is the story of two immortal young lovers who guard a pharaoh's tomb for eternity in exchange for eternal life. But, who, or what, is the mechanism that kills everyone who enters the young king's tomb - from tomb robbers in ancient Egypt who met strange deaths, to the team of American archeologists who uncover the tomb in modern times and meet awful deaths? Can the curse be canceled? Is it worth the try, or is there a terrible penalty for trying? And, what happens to the Guardians if they are no longer needed?