Mrs. Azimi is a rich old lady who’s murdered along with her servant in a burglary at her home. Inspector Kavian believes there’s little evidence proving the prime suspect, a mentally-challenged man named Qassem, was the killer. He decides to set him free and keep him under surveillance in his search for the main culprit. Tehran Café is the key location where Kavian finds clues to solve the mystery after long conversations with Jalal, the story’s most complicated character.