Mystery in Marrakech by Betty Cavanna (1968)
Still she was unprepared when her vague fears were fulfilled, and her friend Felicia was spirited away from the city. Together with Rick, Felicia's brother, Dizzy set out on an anxious trip across the rugged Atlas Mountains to find help. Their journey led them finally to the ancient Casbah of Telouet, a cluster of ghostly spires reaching into the sky that seemed to emanate evil like a witch's castle in a fairy tale. What would they find concealed in its deserted 600 rooms?
Betty Cavanna, who has taken two extensive trips to Morocco, is a favorite author of young people's books. An exciting mystery plot against the striking Moroccan background makes this colorful adventure one of her most appealing stories. (from the inside flap)