TEHRAN—The husband-and-wife team of Mehdi Yazdany and Sarvenaz Heraner were cruising the streets of Iran's sprawling capital in search of targets.

They homed in on a young woman standing at the side of the road looking for a cab. Her hair was covered by a black scarf.

Pulling over, they swung open the rear door and she slipped into their white compact sedan.

"Do you read a lot?" a smiling Ms. Heraner asked the woman as they drove into traffic.

Samira Chigani, 26 years old, was thus introduced to the quirky brainchild of Mr. Yazdany and Ms. Heraner: a mobile reading room and taxi service, complete with chauffeur-librarian.