Set in a rural village in Kerala, Vashyashasthram unfolds as a bedtime story narrated by a grandmother to her grandchild. The tale follows Chandrappan, a desperate man in his late twenties who steals a sacred temple idol believed to house a mischievous spirit. As villagers, driven by fear, superstition, and led by opportunistic temple authorities, hunt for the missing deity, Chandrappan takes refuge in a secluded house where he meets Bhama, a confident and enigmatic sex worker. A strange bond forms between them, complicated by the idol’s presence.

As ritualistic violence escalates and the temple committee schemes to profit from the incident, belief begins to blur with reality. In the climax, Bhama is perceived to transform, embodying the idol’s spiritual power. The idol is ultimately commodified, now believed to be Bhama herself, leaving unanswered whether anything has truly changed for her.