Unable to bear the sight of her husband, who runs a convenience store, struggling with shoplifting, Mari approaches the security company where her sister Anna's husband works for advice. Worried about her sister, Anna decides to work at the store as a shoplifting detective together with Mari, who has no experience... After the two start working at the store, they catch several shoplifters and feel relieved, but Mari makes a mistaken arrest. Deceived by the shoplifter they saw with their own eyes, the two learn that a large theft gang is behind them...