The Coiled Viper (The Secrets of Droon #19)

Lord Sparr is back... and meaner than ever! This time, he is in search of the Coiled Viper, an ancient magical object of unknown, incredible power. Princess Keeah and her Upper World friends - Eric, Neal, and Julie - know they have to stop Sparr from uncovering the Viper. But there's one little catch. The Viper can't be found in Droon... because it's hidden somewhere in the Upper World!