Amira & Hamza by Samira Ahmed

Amira and Hamza are back in this epic sequel, which takes readers on a thrilling magical adventure as the siblings face their most terrifying and formidable opponent yet.
All human and jinn kind shall bow down to me. Control the Ring, control the worlds.

Amira and Hamza have returned from Qaf, the magical Jinn world, as triumphant heroes-and life has been pleasantly quiet. Too quiet. Hamza is determined to have one last monumental, epic adventure before summer ends. But when sneaking off to explore an old, abandoned castle goes from life-changing adventure to potentially deadly, Amira and Hamza find themselves in the middle of another dangerous quest to save the worlds. One they didn't bargain for.

The siblings are brought face to face with the evil dev, Ahriman, angry and out for revenge. And if Amira and Hamza thought Ifrit was bad, his dad Ahriman, the last in an ancient line of fire spirits, is far worse. Ahriman kidnaps Hamza and forces him to help locate the lost Ring of Power, an ancient and mysterious artifact that will allow him to rule the universe. Desperate to save her brother, Amira must outsmart perilous traps and confounding puzzles in a race against time to retrieve the artifact before Ahriman does... or say goodbye to Hamza and their world forever.