A wrong-number call for a fictional detective pulls a reclusive writer into Tehran's hidden war of ideas. Hired to protect a young man, the "filtered" son of a fanatical professor, Dariush Qazvini begins a shadowing that becomes an obsession. As he trails the professor through the city, he discovers a secret text being walked onto the streets themselves, a message about the nature of reality, control, and the mind's last sanctuary.