"DON'T turn. Don't stop. This is Maitland behind you. Just go right ahead. Tell me where you live and stand by to let me in the moment I get there."Mark Donovan didn't turn, and he didn't stop; he went straight on through the darkness of a foggy night. He had recognised that tense voice. The speaker was Dr. Steel Maitland right enough--whom he had last seen in Cairo! But his heart began to beat a shade faster when he spoke: Maitland was no more than a pace to the rear.