From BigFinish.com :
“You will be always looking in the wrong place. I have searched through all of Time and I cannot find it.”
The search for the Key to Time has stalled: the next segment does not appear to exist anywhere in the Universe. Forced into a temporary alliance with one of his greatest enemies, the Doctor suggests a course of action that is a validation of chaos itself.
Thrown at random across Space and Time, the Doctor and Amy arrive in 9th Century Sudan, where the greedy Lord Cassim is hoarding gold from the Legate of the Caliph. But why does Cassim look so familiar? What is the mysterious Djinni that lives out in the desert? And why does it need so much treasure?