The Desert Sun, An Archer Adventure, Book 5

The Desert Sun, a sacred gem, is stolen from the kingdom of Saphra in the parallel world of the immortals. After two crystal masters fail to find the thief or the gem, they're forced to believe the thief took the gem into the parallel world of Archer’s childhood.
Always eager for an adventure, Archer and Aradia quickly learn there’s more at stake than the theft of the precious gem. Because the theft occurred shortly before the coronation of Saphra’s new king, it’s important The Desert Sun be found or Saphra will not only lose its heir, It will lose its desert heritage.

Saphra’s crystal master gives Archer and Aradia the details of the theft but neglects to tell them she's sending them into the past to begin the adventure of their lives. They'll have to search for the yellow gem on the vast Egyptian desert with an untrustworthy and mysterious guide. The treacherous journey pits Archer and Aradia's skills against desert bandits, roaming lions, Death Stalker scorpions, terrifying thought forms and a room full of cobras before they arrive at the ruins of a dead city lost in time. It’s here that they not only discover the secret of Egypt's pyramids but unravel a deadly plot against Saphra and the rightful heir to Saphra's throne.