The Eye of the Forest (Children of the Lamp #5)

In their latest adventure, John and Philippa Gaunt find themselves tangled up in a spellbinding mystery that takes them deep into the heart of the Amazon jungle. When a collection of Incan artifacts goes missing, the Blue Djinn of Babylon dispatches the twins and Uncle Nimrod to recover them. Along the way, though, John and Philippa encounter their friend Dybbuk, who was drained of his djinn powers but is determined to get them back.