The Day of the Djinn Warriors is the fourth novel and deals with more of the Sachertorte family's past, as well as the encounter with the newly changed Layla Gaunt. Dealing with thefts, hauntings and a red-hot mystery, it is a race against time for John and Philippa Gaunt to outwit the wicked Iblis. But can the djinn twins stop Iblis now he has awoken the ancient warriors of a long-dead emperor from their sleep? John and Philippa attempt to rescue their mother from her fate as the Blue Djinn of Babylon (a djinn that is beyond good and evil, who has powers over all.) They discover that an aging curse has been placed on their father and if the twins are gone too long, he will rapidly become an old man. As the twins and their friends travel around the globe on their rescue mission, they notice that something very strange is happening: An evil force has awakened the terracotta warriors created by an ancient Chinese emperor, and someone with very bad intentions has cast a spell possessing the soldiers with wicked spirits. And now, the very fate of the world hangs in the balance.
Meanwhile, museums all over the world are reporting robberies of valuable jade artifacts from their collections, as well as bizarre hauntings.