The Riddle of The Rajah's Ruby: 3 (The Young Adventurers) . This series circles around the twins, Nick and Katie, who along with their friends set out on incredible adventures and mysterious endeavours.

The third part in the series sees Nick and Katie on a journey to save their friends, Sophie and David, from trouble when the possession of a cursed ruby causes them to fall into difficult circumstances. After receiving the news that their friends have inherited the mysterious ruby, they are over the moon with excitement. They plan to meet them to inspect the rock with their own hands. But before that happens, their friends are kidnapped. The task at hand is to save them from their captors before it is too late. The book talks about whether they'll be successful, or be sucked into the dangerous world of greed.

Nick and Katie have to follow their friends' trail using the assistance offered by a few clues that come their way. This book describes the exciting, dangerous, adventurous and thrilling journey experienced by the twins.